Using DAO (Data Access Objects) Code _ Visual Basic 6 (VB6

Search

Level:

Home › Tutorials

Using DAO (Data Access Objects) Code

This tutorial describes how you can use DAO

code directly within your VB6 application

instead of being tied to a Visual Basic control.

Originally Written By TheVBProgramer.

Why Use Code Instead of the Data Control?

The advantage of using the data control is that you can put

together solid data entry forms without writing much VB code.

This method works well for small, one-time projects that need

to be completed quickly.

The disadvantage of using the data control is that once the

project is completed, it is not always easy to modify the data

entry form or adapt the finished form for another data entry

project. Also, forms built using the data control are not

always easy to debug or maintain because most of the action goes on in the data control itself. If you think your

project needs to be modified or maintained by other programmers, the data control might not be your best choice.

The advantage of using complete VB code to produce data entry forms is that you have total control over allaspects of the process. You decide when to open the database and recordset, and you control the read andwrite operations as well. This capability can be a real advantage in multiuser (file-sharing) settings whereincreased traffic can cause locking conflicts in programs that use the data control. Another advantage ofusing VB code for your data entry forms is that you can create generic code that you can reuse in all yourdatabase projects. When you have a fully debugged set of data entry routines, you can quickly create newforms without much additional coding. Because the form rely on generic routines, they are also easy tomodify and maintain in the future. The primary drawback for using VB code to create data entry forms is that you have to handle all processesyourself; you can assume nothing. For example, locating and updating a single record in a data tablerequires that you account for all of the following processes:

ℜ• Opening the databaseℜ• Opening the recordsetℜ• Locating the requested recordℜ• Loading the input controls from the recordsetℜ• Handling all user actions during the data entry processℜ• Writing the updated controls back to the recordset

You also need a way for the user to browse the data. In giving up the data control, you give up its VCR-stylenavigation arrows. Despite this added responsibility, writing your data entry forms with VB code gives you much greater controlover the process and can result in a form that is easy for both programmers and users to deal with. Even

Ads by Google Visual Basic Download VB VB Programming VB Source Code

Ads by Google

PDF Writer for VB

Create, display, print, edit, merge Royalty-freedistribution. Try now!

www.synactis.com

Visual Basic 6 (VB6)

3/31/2011 Using DAO (Data Access Objects) Code |…

vb6.us/…/using-dao-data-access-object… 1/72

though you have to do a good bit of coding to create new data management routines, these routines canoften be reused in future projects with a minimum of re-coding.

The Sample Database (EMPLOYEE.MDB)

This document shows you how to process an Access database using code alone. The database is named"EMPLOYEE.MDB", and is based on the sample employee file used in the tutorials on sequential files. EMPLOYEE.MDB contains three tables: EmpMast, DeptMast, and JobMast. The tables are structured asfollows: EmpMast table:

Field Name DataType Comments

EmpNbr AutoNumber Primary Key. Uniquely identifies each employee inthe database.

EmpFirst Text (50) Employee's first nameEmpLast Text (50) Employee's last nameDeptNbr Number (Long Integer) Foreign Key to PK of DeptMast table. Identifies

which department the employee works in.JobNbr Number (Long Integer) Foreign Key to PK of JobMast table. Identifies the

employee's job.HireDate Date/Time Date the employee was hiredHrlyRate Number (Single) Employee's hourly rate

SchedHrs Number (Single) The number of hours per week the employee is scheduled to

work.

DeptMast table:


DeptNbr Number (Long Integer) Primary Key; uniquely identifies each department inthe database. The PK index was renamedidxDeptNbrPK in the Access interface (see below).

DeptName Text (50) The name of the department. A non-unique indexwas established on this field, and the index wasrenamed idxDeptName.

Location Text (50) The department's location (could be a building, suitenumber, floor, etc.)

JobMast table:


JobNbr AutoNumber Primary Key; uniquely identifies each job in thedatabase. The PK index was renamedidxJobNbrPK.



JobTitle Text (50) The job title (description). A non-unique index wasestablished on this field, and the index was renamedidxJobTitle.

MinRate Number (Single) The minimum hourly rate that somebody working inthis position is usually paid.

AvgRate Number (Single) The average hourly rate that somebody working inthis position is usually paid.

MaxRate Number (Single) The maximum hourly rate that somebody working inthis position is usually paid.

How to Rename Indexes in the Access UI

Note that in the screen-shot of the table design for DeptMast, DeptNbr was set up as the primary key, andthat a non-unique index was established for DeptName (this will facilitate faster searching for a recordwhere the DeptName contains a particular value and will allow easier browsing of the DeptMast table inDeptName sequence).

To examine information related to the indexes that you set up for a table, click the Indexes icon (looks like alightning bolt) on the Access toolbar.

Clicking the Indexes icon causes the Indexes dialog box (shown below) to be displayed. Note that under the"Index Name" column, I renamed the indexes. The Index Name for the DeptNbr field was changed from"PrimaryKey" to "idxDeptNbrPK" (the Access default index name for the primary key field is "PrimaryKey")and the Index Name for the DeptName field was changed from "DeptName" to "idxDeptName" (the Accessdefault index name for non-primary key fields is the same as the Field Name).



The DAO Object Model

An essential part of learning how to program Access database applications is to gain a working knowledgeof the DAO (Data Access Objects) object model, shown on the following page. An object model is arepresentation, or conceptual map, of an object's functionality in terms of an object hierarchy. The objects inthe object model are said to be "exposed", meaning that they are items that can be programmed orcontrolled. The objects in the object model are organized into various levels. You can think of these levels as tiers in ahierarchy. The topmost tier in the DAO object model is the JET database engine itself (DBEngine). Thesecond tier consists of a high-level categorization of objects. The third, fourth and fifth tiers, etc. include avariety of different objects used to access the functionality that the second-tier objects contain. You traversethe tiers to find the objects you want to use. A group of similar objects can be combined in the hierarchy as a collection. In general, the plural names("Databases", "Recordsets", etc.) are collections and the singular names ("Database", "Recordset", etc.)are objects with the collection.

Collection Syntax

To refer to an object in a collection, the syntax is: CollectionName.Item("Key") -- or -- CollectionName.Item(index)

Item is the default method for all collections; therefore .Item can always be dropped from the above syntax,reducing it to: CollectionName("Key") -- or -- CollectionName(index)

An object's Âkey is a string that uniquely identifies that object in the collection. For example, the DeptNbrfield in the collection of fields of a table could be referred to as Fields("DeptNbr"). The index refers to theobject's ordinal position in the collection, which could change if items are added to or removed from thecollection. If the DeptNbr field is the first field in the Fields collection, it could be referred to as Fields(0).(Note: It is generally preferable to use the key rather than the index to access items in a collection. Since theindex for an item in a collection is subject to change, its use would be limited to situations such as where youare looping through the items one by one, perhaps to display information about each item, or just to verifywhat items are in the collection.)



In looking at the DAO object model, you see a good number of collections and objects. Each of theseobjects has numerous methods and properties. However, in a typical VB/DAO application, you will onlyneed to deal with a handful of these collections and objects. Most likely, you will use Workspace object(indirectly), the Database object, and the Recordsets, TableDefs, and possibly QueryDefs collections.The collections and objects used in the sample project presented in this document, along with theirproperties and methods will be discussed as they are encountered, as we examine the processing thattakes place in each of the project's forms. Good reference material for each of these items can be found in the Access help system. In addition, thereare a number of good reference books on JET / DAO. One of the best books on the subject is the "MicrosoftJet Database Engine Programmer's Guide" by Dan Haught and Jim Ferguson (Microsoft Press, 1997).

The DAO (Data Access Objects) Object Model

Using DAO in Your VB Project

VB projects that will process an Access-style (JET) database must include a reference to Microsoft DAO 3.51 Object Library.



To include this reference, go to the VB Project menu and select References. From the resulting dialog box, check that reference

(shown below):

Note: When you use the data control, setting this reference is not necessary (VB will set it automatically).

The Sample Project (prjDAODemo)

The sample project contains seven forms and one standard module, as summarized below. Forms:

Name Description

frmSplash The splash screen

frmMainMenu The main menu, or "switchboard" screenfrmHelp The form where help files are displayedfrmDeptMaint Used to add, change, or delete records from the DeptMast tablefrmJobMaint Used to add, change, or delete records from the JobMast tablefrmEmpMaint Used to add, change, or delete records from the EmpMast tablefrmReportMenu Allows the user to select a (Crystal) report to be printed

Modules:

Name Description

frmSplash Standard module containing public variables, subs, and functions.

modCommon



We will look at each form in the sample project in turn, but first, let's take a look at the code that's in thestandard module (listed a little further below). In the general declarations section, you see the statement

Public gobjEmpDB As Database

"Database" is a specific type of object variable. Once the Microsoft DAO 3.51 Object Library has beenincluded in your project, variables defined as any of the object types present in the DAO object model(Database, TableDef, Recordset, Field, etc.) can be used in the project. In addition to the CenterForm routine and the GetAppPath function, there are two database-related routines,one to open the database and one to close it. In this project, each form that uses the database calls theOpenEmpDatabase sub when the form is loaded and calls the CloseEmpDatabase sub when the form isunloaded.

The OpenDatabase Method

The Sub OpenEmpDatabase contains the single statement:

Set gobjEmpDB = OpenDatabase(GetAppPath() & "EMPLOYEE.MDB")

Recall that gobjEmpDB was declared as a "Database" variable, which is a specific type of object variable. Unlike standard VB

variables such as "Integer" and "String", object variables must be initialized with the Set statement. The Set statement

establishes a valid reference to an object variable.

OpenDatabase is a method of the Workspace object in the Workspaces collection (and of course Workspaces is a collection of

the DBEngine object). A Workspace object exists for each active session of the Jet database engine. A session delineates a

sequence of operations performed by MS Jet. A session begins when a user logs on and ends when a user logs off. When your

DAO application starts executing, the first Workspace object of the Workspaces collection (referenced as Workspaces(0)) is

already created. Workspaces(0) is also referred to as the default workspace.

Since the DBEngine object and the default Workspaces item (Workspaces(0)) are automatically available to an application that

includes the reference to the Microsoft DAO 3.51 Object Library and do not need to be explicitly referenced when using

"OpenDatabase", although they could be, as in the following statement:

Set gobjEmpDB = DBEngine.Workspaces(0).OpenDatabase(GetAppPath() & "EMPLOYEE.MDB")

The OpenDatabase method requires a string argument evaluating to the name of the database file to beused, followed by optional arguments not used in the example above. It opens the requested database fileand returns an appropriate object reference to the Database variable. The above statement opens theEMPLOYEES.MDB database file, located in the same path as the VB program, and sets up the variablegobjEmpDB to reference this database.

The Database Object

Once you have a valid reference to the database via the OpenDatabase method, you can then use thevarious methods and properties of the Database object in code, using the Database object variable.Methods commonly used with the Database object are Execute, Close, and OpenRecordset. The



OpenRecordset method is by far the most commonly used method of the Database object and is usedliberally in several of this project's forms. OpenRecordset will be discussed a little later, when those formsare looked at. The Execute method is used to execute SQL statements that return no rows on the database. This basicallyincludes non-SELECT queries: DDL queries such as CREATE TABLE or DROP TABLE, and actionqueries such as UPDATE or DELETE. The Execute method requires a string argument containing a validSQL statement. For example, the following statement would give all of the employees a 10% raise:

gobjEmpDB.Execute "UPDATE EmpMast " _

& "SET HrlyRate = HrlyRate * 1.1"

Note: The Execute method, while quite useful, was not used in the sample project. The Close method simply closes the database and is coded as gobjEmpDB.Close (see theCloseEmpDatabase Sub).

The Nothing Keyword

When you are done using an object variable (be it a database object variable, a recordset object variable, or any other type of

object variable), you should set that object variable to the VB keyword Nothing, which disassociates an object variable from the

actual object and releases memory and system resources associated with the object to which the variable refers. Thus, when

the database is closed, the Database object variable should be set to Nothing, as in:

Set gobjEmpDB = Nothing

Code for the standard module modCommon:

Option Explicit


Public gintHelpFileNbr As Integer

'-----------------------------------------------------------------------

-

Public Sub OpenEmpDatabase()

'-----------------------------------------------------------------------

-


End Sub

'-----------------------------------------------------------------------

-



Public Sub CloseEmpDatabase()

'-----------------------------------------------------------------------

-

gobjEmpDB.Close


End Sub

'-----------------------------------------------------------------------

-

Public Sub CenterForm(pobjForm As Form)

'-----------------------------------------------------------------------

-

With pobjForm

.Top = (Screen.Height - .Height) / 2

.Left = (Screen.Width - .Width) / 2

End With

End Sub

'-----------------------------------------------------------------------

-

Public Function GetAppPath() As String

'-----------------------------------------------------------------------

-

GetAppPath = IIf(Right$(App.Path, 1) = "\", App.Path, App.Path & "\")

End Function

The Splash Screen (frmSplash):

The splash screen, named "frmSplash" is shown below (design-time). This form was established as the startup object for this

project. It contains a Timer control named tmrSplash. When the timer's Timer event fires, control is transferred to the Main Menu

form.



Code for frmSplash:

Option Explicit

'-----------------------------------------------------------------------

-

Private Sub Form_Load()

'-----------------------------------------------------------------------

-

CenterForm Me

End Sub

'-----------------------------------------------------------------------

-

Private Sub tmrSplash_Timer()

'-----------------------------------------------------------------------

-

tmrSplash.Enabled = False

frmMainMenu.Show

Unload Me

End Sub

The Main Menu Screen (frmMainMenu):

The main menu, or "switchboard" screen, named "frmMainMenu" is shown below. There is no database-related processing in

this form, either. It contains an array of six command buttons, named cmdMainMenuOpt, indexed 0 to 5.



In looking at the code in cmdMainMenuOpt_Click, you can see that for command buttons 0 through 3, the appropriate form is

shown.

For command button 4 (Help), a sub named ShowHelpForm is called. The ShowHelpForm sub is also called when the user

presses the F1 key (see the Form_KeyDown event procedure). Recall that in order for the Form_KeyDown event to work, you

should set the form's KeyPreview property to True. In the ShowHelpForm sub, you see that the public variable gintHelpFileNbr is

set to 1. The reason for this will be explained a further below, when we look at the Help form. The Exit button

(cmdMainMenuOpt(5)) simply ends the application.

Code for frmMainMenu:

Option Explicit

'-----------------------------------------------------------------------

-


'-----------------------------------------------------------------------

-

CenterForm Me

End Sub

'-----------------------------------------------------------------------

-

Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)

'-----------------------------------------------------------------------

-



If KeyCode = vbKeyF1 Then

ShowHelpForm

End If

End Sub

'-----------------------------------------------------------------------

-

Private Sub cmdMainMenuOpt_Click(Index As Integer)

'-----------------------------------------------------------------------

-

Select Case Index

Case 0

frmEmpMaint.Show vbModal

Case 1

frmDeptMaint.Show vbModal

Case 2

frmJobMaint.Show vbModal

Case 3

frmReportMenu.Show vbModal

Case 4

ShowHelpForm

Case 5

End

End Select

End Sub

'-----------------------------------------------------------------------

-

Private Sub ShowHelpForm()

'-----------------------------------------------------------------------

-

gintHelpFileNbr = 1

frmHelp.Show vbModal

End Sub

The Help Screen (frmHelp):

The Help screen, named "frmHelp", displays an appropriate help file in a rich textbox. There are four helpfiles for this application named EDMHELP1.DOC, EDMHELP2.DOC, EDMHELP3.DOC, andEDMHELP4.DOC. (Despite their DOC extensions, these files were saved in Rich Text format.) These filescontain help for the Main Menu form, Employee Maintenance form, Department Maintenance form, and JobMaintenance form, respectively (actually, that's what they should contain; they really just contain a sentenceor two, for the purposes of this sample application). As you saw in the code for the Main Menu form, the public variable gintHelpFileNbr was set prior to showingfrmHelp. The frmHelp form then uses that number in the Form_Load event to determine which help file todisplay in the rich text box. Note how this line in the Form_Load event generates the appropriate file name:



strHelpFileName = GetAppPath & "EDMHELP" & gintHelpFileNbr & ".DOC"

The About button shows the "About" message box. The OK button unloads the form, thus returning control tothe calling form. A run-time screen-shot as well as the code for frmHelp are shown below:

Code for frmHelp:

Option Explicit

'-----------------------------------------------------------------------

-


'-----------------------------------------------------------------------

-

Dim strHelpFileName As String

CenterForm Me

strHelpFileName = GetAppPath & "EDMHELP" & gintHelpFileNbr & ".DOC"

rtbHelp.LoadFile strHelpFileName, rtfRTF

End Sub

'-----------------------------------------------------------------------

-

Private Sub cmdOK_Click()

'-----------------------------------------------------------------------

-



Unload Me

End Sub

'-----------------------------------------------------------------------

-

Private Sub cmdAbout_Click()

'-----------------------------------------------------------------------

-

MsgBox "DAO (Data Access Objects) Demo" & vbNewLine _

& "Employee Database Maintenance" & vbNewLine _

& "Copyright " & Chr$(169) & " 2000-2005 thevbprogrammer.com", _

vbInformation, _

"About"

End Sub

The Data Entry Screens (frmDeptMaint, frmJobMaint, frmEmpMaint)

In the data entry screens for the demo application, the user can browse through the records in the table (one record per screen)

using "First Record", "Previous Record", "Next Record" and "Last Record" buttons. In addition, the user can perform a search to

jump to a particular record based on entered criteria. The user can add, update, or delete a record using "Add Record", "Update

Record", and "Delete Record" buttons respectively.

Initially, the user can "look but not touch" the data, as they perform various move or search operations. When the user initiates

an add or an update, the controls (generally textboxes) for the data fields as well as the "Save", "Undo" and "Cancel" buttons

become enabled; all other buttons become disabled.

As the user enters or modifies data in the controls, field-by-field data validation is performed. This means that the user cannot

move to a specific control until all the controls before it pass edit (for example, if a form contained first name, last name, and

address fields, the user could not move on to the last name field until the first name field was entered and the user could not

move on to the address field until the last name field was entered).

As indicated above, when an add or update is in progress, the user has three options available via the "Save", "Undo" and

"Cancel" buttons:

If the user clicks the "Accept" button, provided that all entries pass validation, the record is added or updated in the database

table and the form controls are set back to their original state (textboxes and Accept, Undo, and Cancel buttons are disabled, all

other buttons are enabled).

If the user clicks the "Undo" button instead, the controls on the form are re-populated with the corresponding fields from the

current record (if doing an update) or the controls on the form are cleared (if doing an add). The form remains in a state in which

the user can add or modify data.

If the user clicks "Cancel", the fields of the previously current record are re-assigned to their corresponding textboxes on the

form, and, as with the "Save" button, the form controls are set back to their original state (textboxes and Save, Undo, and

Cancel buttons are disabled, all other buttons are enabled).

It should be noted that the data entry approach implemented by the demo application as described above is a restrictive

approach that attempts to control the user's actions to the greatest degree possible. This approach may be appropriate in some

cases but not in others â€“ it depends on the type of application as well as what the users are familiar with. If we were to



"loosen" things up a bit, the field-by-field validation could be eliminated and validation would be done only when the record is

about to be saved (this way the user could move around on the form; skip fields then come back to them, etc.). If we were to

loosen things up further, we could eliminate the "two state" approach between browsing and updating â€“ in other words, have all

fields open all the time and not make the user explicitly click a button to initiate an update. Regardless of the approach used,

your application will need to detect when the user has made changes and ensure the integrity of the data.

Implementing Field-by-Field Validation

In order to implement field-by-field validation as described above, the following points should be considered:

ℜ• All controls on your form should have their TabIndex property set such that the tabbing order is correct.

ℜ• The MaxLength property should be set for all textboxes where appropriate.

ℜ• A form-level integer variable to store the TabIndex property of the currently active field should be declared (in the sample

application it is called intCurrTabIndex).

ℜ• A form-level Boolean variable indicating whether or not a validation error occurred should be declared (in the sample

application it is called blnValidationError).

ℜ• A routine (Sub) which contains validation code for all enterable fields should be coded (in the sample application this Sub

is called ValidateAllFields).

ℜ• Logic for the GotFocus, KeyPress (if necessary), and Change events should be coded for each textbox; logic for the

Validate event should be coded for the last textbox.

The basic logic coded in each of the events is as follows:

GotFocus:

(1) Set intCurrTabIndex to the TabIndex property of this textbox.

(2) Call the ValidateAllFields routine.

(3) If there was a validation error (mblnValidationError = True), exit now (skipping the next two statements).

(4) Set the SelStart property of this textbox to 0.

(5) Set the SelLength property of this textbox to the length of the text currently in this textbox.

Note: The first three statements above can be omitted in the GotFocus event of the first textbox to be validated. Those

three statements are basically saying to the user "You can't come here until you've dealt with your previous errors."

Statements 4 and 5 cause the text in the textbox to be highlighted when it receives focus.

KeyPress:

Place optional code in here to filter out undesirable characters entered by the user (for example, if a fields is to contain only

numeric digits, you can filter out anything else). You can also change the character entered by the user (the most common

conversion done here is to convert all lowercase characters entered by the user to uppercase).

Change:

If the length of the text in this field is equal to its MaxLength property, then set the focus to the next enterable field. (This

provides an auto-tab feature for the form fields.)

Validate:

Introduced in VB6, the Validate event can be used in conjunction with the CausesValidation property toprevent a control from losing the focus until certain criteria are met. The Validate event only occurs whenthe control which is about to receive the focus has its CausesValidation property set to True. TheValidate event fits into the field-by-field data entry scheme for the last field to be validated. (In the sampleapplication, the Validate event is coded for the last data entry field, and the Save button has itsCausesValidation property set to True. When the user tabs out of the last field and into the Save button,the Validate event fires for the last field. If the Validate event deems that the field has not passed edit,the Cancel parameter of the Validate event is set to True, causing focus to remain on that field.) Note:Some resources advocate the use of the Validate event for all of the fields to be validated; this is not



done in the sample application because the Validate event will fire whether you are moving backwardsor forward through the fields on the form â€“ the intention in the sample application is to validate onlywhen moving forward.

ℜ• The basic logic (in pseudocode) for the ValidateAllFields Sub is as follows:

mblnValidationError = False

If FIELD_1 is NOT valid Then

mblnValidationError = True

MsgBox "Error in Field 1"

FIELD_1.SetFocus

End If

If (mintCurrTabIndex = FIELD_2.TabIndex) _

Or (mblnValidationError = True) Then

' The user has either just tabbed to FIELD_2 (in which case FIELD_2 is

' not yet ready to be checked), or FIELD_1 has an error. In either case,

' there is no point in continuing ...

Exit Sub

End If

If FIELD_2 is NOT valid Then


MsgBox "Error in Field 2"

FIELD_2.SetFocus

End If

If (mintCurrTabIndex = FIELD_3.TabIndex) _

Or (mblnValidationError = True) Then

' The user has either just tabbed to FIELD_3 (in which case FIELD_3 is

' not yet ready to be checked), or FIELD_2 has an error. In either case,

' there is no point in continuing ...

Exit Sub

End If

. . .

If LAST_FIELD is NOT valid Then


MsgBox "Error in Last Field"

LAST_FIELD.SetFocus

End If

' End of Sub

The information presented above to implement field-by-field data validation can be simplified by the use of control arrays,

particularly if all of the data entry fields are textboxes. By using a textbox control array, all textboxes would share the same

GotFocus, KeyPress, Change, and Validate event. You would know which textbox you were "on" by testing the Index argument

that is passed into the event. Similarly, the logic for the ValidateAllFields Sub would also be simplified.

The sample application uses control arrays on two of three data entry forms.

The Department Maintenance Form (frmDeptMaint):



The Department Maintenance form, shown below, enables the user to perform maintenance on theDeptMast table. Processing note: The department number field, while it must be unique, is not an autonumber field â€“therefore, during an "add", the user will have to enter it. During an update, the user should not be permittedaccess to the department number.

The code behind this form introduces a number of DAO methods and properties as discussed below.

The OpenRecordset Method

The OpenRecordset method of the Database object is used to establish a reference to a set of records, such as a table or the

results of a query. This set of records is assigned to a Recordset object variable, and can then be processed record by record

as if it were a file. The Recordset object is temporary object; it is created by the OpenRecordset method in code and is

destroyed when it is closed or set to Nothing (it is not a "permanent" object like a table or saved query, although it is derived

from these sources). The Recordset object is similar to what is called a "cursor" in other database systems.

The syntax is:

Set RecordsetVariable = DatabaseVariable.OpenRecordset (source, type,

options, lockedits)

The source argument is a string representing the name of the table or query you want to refer to. A SQL statement itself can

also be used here.

The type argument is a constant specifying the way you want to process the recordset. The recordset can be processed as a

table, dynaset, or snapshot, and the constants dbOpenTable, dbOpenDynaset, or dbOpenSnapshot respectively are used

to refer to these. If this argument is omitted, Jet will default to the type it deems most appropriate, based on the source. The

three types of recordsets are compared in the table a little further below.

The options and lockedits arguments are optional and will not be used in the sample application.

Following are two statements that employ OpenRecordset, pulled from this formâ€™s code.



The statement

Set mobjDeptRst = gobjEmpDB.OpenRecordset("DeptMast", dbOpenTable)

enables the recordset object variable mobjDeptRst to reference the table "DeptMast" in the EMPLOYEES.MDB. This statement

assumes that a valid reference to the Database variable gobjEmpDB has been set via the OpenDatabase method (discussed

previously) and that the variable mobjDeptRst as been declared as a Recordset object variable (as in Private mobjDeptRst As

Recordset).

The statement

Set objTempRst = gobjEmpDB.OpenRecordset _

("SELECT COUNT(*) AS EmpCount FROM EmpMast " _

& "WHERE DeptNbr = " & mobjDeptRst!DeptNbr)

enables the recordset object variable objTempRst to reference the results of the SELECT query coded as the source argument.

Again, this example assumes that the Database variable gobjEmpDB has been properly set, and that objTempRst has been

declared as a Recordset variable (i.e., Dim objTempRst As Recordset). The type argument is omitted, so Jet should default to

the dynaset type in this case. The meaning of mobjDeptRst!DeptNbr will be discussed shortly.

Types of Recordsets

Recordset

Type

Source Constant Advantages

Drawbacks

Table dbOpenTable ℜ• Allows direct access to a

database table

ℜ• Can use indexes

ℜ• Searches are fast

ℜ• Can update records in the

underlying table

ℜ• can reference a single table

only

ℜ• can search only on available

indexes (using the "Seek"

method)

ℜ• can't limit the number of

records returned

Dynaset dbOpenDynaset ℜ• Can select specific records

and fields

ℜ• Can use SQL statements to

do joins

ℜ• Search can be based on

any field (using the "Find"

methods)

ℜ• Records in the underlying

table(s) may or may not be

updateable

ℜ• Searches are slower than

Table type

ℜ• Can't make use of indexes

Snapshot dbOpenSnapshot ℜ• Similar to advantages of

Dynaset

ℜ• Faster because it is a

memory-based copy of the

data

ℜ• Read-only

Once a valid reference to the desired recordset has been established via the OpenRecordset method, you can then use the



various methods and properties of the recordset object in code, using the recordset object variable. Methods include the Move

methods, Seek (for table-type recordsets), the Find methods (for dynaset-type recordsets), AddNew, Edit, Update, and Delete.

Properties include EOF/BOF, Index, and Bookmark. The methods and properties are referenced in code using standard VB

"dot" notation, as will be shown in several of the following examples.

The following examples assume that mobjDeptRst has been declared as a Recordset variable, as in:

Private mobjDeptRst As Recordset

and that mobjDeptRst has been opened with the OpenRecordset method, as in:


The Move Methods

The four Move methods (MoveFirst, MovePrevious, MoveNext, and MoveLast) cause the recordset tomove to the first, previous, next, or last record, respectively, making that record the current record. Youwould code statements like the following:

mobjDeptRst.MoveFirst

mobjDeptRst.MovePrevious

mobjDeptRst.MoveNext

mobjDeptRst.MoveLast

Using the BOF and EOF Properties

When you are moving forward with MoveNext, there is the possibility that you will reach the end of therecordset, and you don't want to move past it. If you move past the end, there will be no current record, whichwill result in errors if you try to retrieve data from the recordset. Therefore, you should use the EOF (end offile) property of the recordset to test for this. When browsing the recordset, if EOF is true, the commonsolution to move to a valid record is to move to the last record:

mobjDeptRst.MoveNext

If mobjDeptRst.EOF Then


End If

Similarly, when you are moving backward with MovePrevious, there is the possibility that you will reach thetop, or beginning, of the recordset, and you don't want to move past that. If you move past the beginning,there will be no current record, which will result in errors if you try to retrieve data from the recordset.Therefore, you should use the BOF (beginning of file) property of the recordset to test for this. Whenbrowsing the recordset, if BOF is true, the common solution to move to a valid record is to move to the firstrecord:

mobjDeptRst.MovePrevious

If mobjDeptRst.BOF Then




End If

Note: When you use the same object reference in multiple statements, you may prefer to enclose the code in a With/End With

block, as follows:

With mobjDeptRst

.MoveNext

If .EOF Then

.MoveLast

End If

End With

The RecordCount Property

For table-type recordsets, the RecordCount property will reflect the actual number of records in the table after OpenRecordset is

executed. For dynaset-type recordsets, the RecordCount property reflects the number of records "visited". This means that for a

dynaset, after OpenRecordset is executed, the first record is the current record, and the RecordCount property will have a value

of 1. If you want the full count, you should use the MoveLast method on the recordset (you can follow that with a MoveFirst to

get back to the first record). After the MoveLast, interrogation of the RecordCount property should reveal the full count.

Index, Seek, NoMatch, and Bookmark

The Index property and the Seek method can only be used on table-type recordsets; using them on a dynaset-type recordset

will produce an error like "Object does not support this property or method". The NoMatch property can be used with any type of

recordset (use it after a table Seek or dynaset Find).

The Index property of a table-type recordset refers to the name of the index that you want to use with the table. The Indexes

include the primary key as well as any other indexes you have established. Recall from earlier in this document that two indexes

were set up for the DeptMast table: idxDeptNbrPK and idxDeptName. Indexes are used for two main reasons: (1) to change the

browsing sequence, and (2) to search for a record based on a value in a particular field.

Regarding changing the browsing sequence, consider the following code:

mobjDeptRst.Index = "idxDeptNbrPK"


' The first record in department number sequence

' (the one with the lowest department number) would become current

mobjDeptRst.Index = "idxDeptName"


' The first record in department name sequence (the one closest to "A"

' alphabetically) would become current



In a table-type recordset, if you want to find a record based on a value in a particular field, an index musthave been established on that field (as we saw earlier when the DeptMast table was set up in Access). Youcan then use the Seek method to search for the desired record. The syntax is:

recordsetvariable.Seek "comparison operator", search value

The comparison operator is a string evaluating to one of the five symbols: "=", ">=", "<=", ">", or "<". Thesearch value is the value that you are looking for in the field on which the current index is based.

For example, suppose you wanted to go to the record for department number 220. First, you would make sure that the Index is

set to "idxDeptNbrPK". Then you would do a Seek with an equal ("=") comparison for the value of 220:


mobjDeptRst.Seek "=", 220

Now suppose you wanted to go to the finance department. You don't know what the department number is, and you're not sure if

it's called "FINANCE" or "FINANCIAL PLANNING" or something else. First, you would make sure that the Index is set to

"idxDeptName". You could then do a Seek with a greater than or equal to (">=") comparison for the value of "FINA". This would

return the first record where the first four letters of the department name were "FINA". The code is:


mobjDeptRst.Seek ">=", "FINA"

Whenever you search for a record, if the system finds it, that record becomes the current record. But there is always the

possibility that the desired record will not be found. To test whether or not the system found your record, you must use the

NoMatch property of the recordset. After a Seek (or a Find in the case of a dynaset), the (Boolean) NoMatch property will be

updated with True or False, indicating whether or not the record was found. "False" is good â€“ it means there was a match! If

NoMatch is True, then the record was not found.

Using NoMatch is all well and good, but it is not enough. Because if NoMatch is True, then there will be no current record. What

would be nice is if you could go back to the record that was current before you attempted the Seek. This is where the Bookmark

property comes in. The recordset's Bookmark property is a binary string representing the current record. If you save the

Bookmark value before you do the Seek (and you should use a Variant variable to save the Bookmark value), then, if the Seek

results in a NoMatch, you can set the Bookmark property back to its old value using the Variant variable. These points are

demonstrated in the code segment below:

Dim lngDeptNbr As Long

Dim vntBookmark As Variant


vntBookmark = mobjDeptRst.Bookmark

lngDeptNbr = Val(InputBox("Enter dept # to find:", "Find Dept #")

mobjDeptRst.Seek "=", lngDeptNbr

If mobjDeptRst.NoMatch Then



Msgbox "Dept # " & lngDeptNbr & " was not found.", vbInformation, "Dept

Not Found"

mobjDeptRst.Bookmark = vntBookmark

End If

Other Notes Regarding Table-type Recordsetsℜ• If you want to search a table for a value in a field that is not indexed, you must open the table as a

dynaset and use one of the Find methods â€“ this will be examined later, when we look at the EmployeeMaintenance form.

ℜ• To avoid "type mismatch" errors in using the Seek method, make sure that your search value is a datatype that is compatible with the indexed field. If your indexed field is numeric, your search value shouldbe a numeric variable or constant; if your indexed field is text, your search value should be a stringvariable or quoted string constant.

Recordset Fields

If you refer back to the DAO Object Model, you will see that Fields is a collection of the Recordset object.Once a recordset is created, its Fields collection is updated to include the fields or columns that make upthe recordset. Recall that an item in a collection is referred to with either its key or with its index. Recall thatthe key is a unique string that identifies an item in a collection â€“ in the case of Fields, it is the Field name;and this is the preferred way to reference a Field in a collection. The index is a number that identifies theposition of the item in the collection.

Recall the collection syntax: CollectionName.Item("Key") -- or -- CollectionName.Item(index)

Recall that you can always drop .Item, reducing the syntax to: CollectionName("Key") -- or -- CollectionName(index)

Since a collection is attached to an object, the object variable, followed by a dot, would appear in front of thecollection name, as in: ObjectVariable.CollectionName("Key") -- or --

ObjectVariable.CollectionName(index)

Therefore, if the field DeptNbr is the first field in the Fields collection of the recordset object mobjDeptRst,the syntax to reference the DeptNbr field is: mobjDeptRst.Fields("DeptNbr") -- or -- mobjDeptRst.Fields(0)

Each object the DAO object model has a default collection; and the default collection name can be droppedfrom the syntax. Since Fields is the default collection of the Recordset object, you can drop .Fields from theabove syntax, reducing it to: mobjDeptRst("DeptNbr") -- or -- mobjDeptRst(0)



If a field name contains blank spaces, the field name must be enclosed in square brackets, as in:rsMyRecSet("[Field With Blanks]")

The Bang (!) Operator

Alternatively, the "bang" operator (!) can be used to specify a programmer-created item of a collection. The syntax is:

ObjectVariable.CollectionName!ItemName

If the collection is the default collection of the object in question, the syntax is then reduced to:

ObjectVariable!ItemName

Therefore, a field in a recordset can also be referenced as:

RecordsetVariable!FieldName

So another way to reference the DeptNbr field of the mobjDeptRst recordset is:

mobjDeptRst!DeptNbr

In the above syntax, note that the field name is not enclosed in either quotes or parentheses. Still, if the fieldcontains blank spaces, the square brackets must be used, as in:

sMyRecSet![Field With Blanks]

In the sample application, the bang operator syntax is used for all field references.

For example, a segment of code that populates the txtDeptField textboxes from the mobjDeptRst recordset could be coded as

follows:

txtDeptField(0).Text = mobjDeptRst!DeptNbr

txtDeptField(1).Text = mobjDeptRst!DeptName

txtDeptField(2).Text = mobjDeptRst!Location

As mentioned earlier, when you use the same object reference in multiple statements, you may prefer to enclose the code in a

With/End With block, as follows:

With mobjDeptRst

txtDeptField(0).Text = !DeptNbr

txtDeptField(1).Text = !DeptName

txtDeptField(2).Text = !Location

End With

The AddNew, Edit, Update, and Delete Methods

The AddNew method creates a temporary buffer containing an empty structure of the recordset record. Ifthe record contains an AutoNumber field, it is populated at this time. In code, you assign values to therecordset fields. When you are done assigning values to the fields, you use the Update method to write the



new record to the recordset. You should save the value of the current record's Bookmark prior to theAddNew, so that you can get back to the current record if the user "undoes" the record-add process. In anyevent, no new record will be added without the Update method. After a new record is successfully added, itdoes not become the current record. To make the new record the current record, use the LastModifiedmethod of the recordset. The Edit method creates a temporary buffer containing the structure and data of the current recordsetrecord. In code, you assign (new) values to the recordset fields. When you are done assigning values to thefields, you use the Update method to update the new record in the recordset. The changes will not "take"without the Update method. The Delete method deletes the current record in the recordset. After the Delete, there is no current recorduntil you use one of the Move methods (such as MoveNext).

The code for the frmDeptMaint form will be shown shortly, but first, the code for the modCommon basmodule will be shown. This module contains declarations for global variables as well as public Sub andFunction procedures that can accessed by any form in the application. The modCommon module containsthe following Sub and Function procedures:

OpenEmpDatabase Sub to open the employee database using the DAO OpenDatabase methodCloseEmpDatabase Sub to close the employee databaseCenterForm Sub to center a form on the screenGetAppPath Sub to get the application path of a fileValidKey Function to validate a keystroke for use in the KeyPress event of a textboxConvertUpper Function to convert an alphabetic character entered in a textbox to uppercase,

used in the KeyPress event of a textboxSelectTextBoxText Sub to highlight the text of a textbox when it receives focus. Used in the

GotFocus event of a textbox.TabToNextTextBox Sub to "autotab" from one textbox to another when maximum number of

characters that can be entered into the first textbox has been reached.

Code for modCommon:

Option Explicit


Public gintHelpFileNbr As Integer

Public Const gstrNUMERIC_DIGITS As String = "0123456789"

Public Const gstrUPPER_ALPHA_PLUS As String =

"ABCDEFGHIJKLMNOPQRSTUVWXYZ,'-"

'------------------------------------------------------------------------

Public Sub OpenEmpDatabase()

'------------------------------------------------------------------------


End Sub



'------------------------------------------------------------------------

Public Sub CloseEmpDatabase()

'------------------------------------------------------------------------

gobjEmpDB.Close


End Sub

'------------------------------------------------------------------------

Public Sub CenterForm(pobjForm As Form)

'------------------------------------------------------------------------

With pobjForm

.Top = (Screen.Height - .Height) / 2

.Left = (Screen.Width - .Width) / 2

End With

End Sub

'------------------------------------------------------------------------

Public Function GetAppPath() As String

'------------------------------------------------------------------------

GetAppPath = IIf(Right$(App.Path, 1) = "\", App.Path, App.Path & "\")

End Function

'------------------------------------------------------------------------

Public Function ValidKey(pintKeyValue As Integer, _

pstrSearchString As String) As Integer

'------------------------------------------------------------------------

' Common function to filter out keyboard characters passed to this

' function from KeyPress events.

'

' Typical call:

' KeyAscii = ValidKey(KeyAscii, gstrNUMERIC_DIGITS)

'

If pintKeyValue < 32 _

Or InStr(pstrSearchString, Chr$(pintKeyValue)) > 0 Then

'Do nothing - i.e., accept the control character or any key

' in the search string passed to this function ...

Else

'cancel (do not accept) any other key ...

pintKeyValue = 0

End If

ValidKey = pintKeyValue

End Function



'------------------------------------------------------------------------

Public Function ConvertUpper(pintKeyValue As Integer) As Integer

'------------------------------------------------------------------------

' Common function to force alphabetic keyboard characters to uppercase

' when called from the KeyPress event.

' Typical call:

' KeyAscii = ConvertUpper(KeyAscii)

'

If Chr$(pintKeyValue) >= "a" And Chr$(pintKeyValue) <= "z" Then

pintKeyValue = pintKeyValue - 32

End If

ConvertUpper = pintKeyValue

End Function

'------------------------------------------------------------------------

-----

Public Sub SelectTextBoxText(pobjTextbox As TextBox)

'------------------------------------------------------------------------

-----

With pobjTextbox

.SelStart = 0

.SelLength = Len(.Text)

End With

End Sub

'------------------------------------------------------------------------

-----

Public Sub TabToNextTextBox(pobjTextBox1 As TextBox, pobjTextBox2 As

TextBox)

'------------------------------------------------------------------------

-----

If pobjTextBox2.Enabled = False Then Exit Sub

If Len(pobjTextBox1.Text) = pobjTextBox1.MaxLength Then

pobjTextBox2.SetFocus

End If

End Sub

Now the code for the Department maintenance form ...

Code for frmDeptMaint:

Option Explicit



'************************************************************************

'************************************************************************

'** **

'** F O R M - L E V E L V A R I A B L E S **

'** **

'************************************************************************

'************************************************************************

Private mobjDeptRst As Recordset

Private mvntBookMark As Variant

Private mstrAction As String

Private mblnOKToExit As Boolean

Private mblnValidationError As Boolean

Private mblnChangeMade As Boolean

Private mintCurrTabIndex As Integer

'************************************************************************

'************************************************************************

'** **

'** E X E C U T A B L E C O D E B E G I N S H E R E . . . **

'** **

'************************************************************************

'************************************************************************

'************************************************************************

'* *

'* FORM Event Procedures *

'* *

'************************************************************************

'------------------------------------------------------------------------


'------------------------------------------------------------------------

CenterForm Me

OpenEmpDatabase



mblnOKToExit = True

cmdFirst_Click

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


cmdHelp_Click

End If

End Sub



'------------------------------------------------------------------------

Private Sub Form_Unload(Cancel As Integer)

'------------------------------------------------------------------------

Dim intResponse As Integer

If Not mblnOKToExit Then

MsgBox "You must complete or cancel the current action " _

& "before you can exit", vbInformation, "Cannot Exit"

Cancel = 1

Exit Sub

End If

mobjDeptRst.Close

Set mobjDeptRst = Nothing

CloseEmpDatabase

End Sub

'************************************************************************

'* DEPT FIELDS *

'************************************************************************

'------------------------------------------------------------------------

Private Sub txtDeptField_GotFocus(Index As Integer)

'------------------------------------------------------------------------

SelectTextBoxText txtDeptField(Index)

If Index > 0 Then

mintCurrTabIndex = txtDeptField(Index).TabIndex

ValidateAllFields

End If

End Sub

'------------------------------------------------------------------------

Private Sub txtDeptField_KeyPress(Index As Integer, KeyAscii As Integer)

'------------------------------------------------------------------------

If KeyAscii < 32 Then Exit Sub

If Index = 0 Then

' dept number - allow only digits

KeyAscii = ValidKey(KeyAscii, gstrNUMERIC_DIGITS)

Else

' dept name or location - force uppercase

KeyAscii = ConvertUpper(KeyAscii)

End If

End Sub

'------------------------------------------------------------------------



Private Sub txtDeptField_Change(Index As Integer)

'------------------------------------------------------------------------

mblnChangeMade = True

If Index < 2 Then

TabToNextTextBox txtDeptField(Index), txtDeptField(Index + 1)

End If

End Sub

'------------------------------------------------------------------------

Private Sub txtDeptField_Validate(Index As Integer, Cancel As Boolean)

'------------------------------------------------------------------------

' this event is only being used for the last field on the form ...

If Index = 2 Then

mintCurrTabIndex = -1

ValidateAllFields

If mblnValidationError Then

Cancel = True

End If

End If

End Sub

'************************************************************************

'* *

'* COMMAND BUTTON *

'* Event Procedures *

'* *

'************************************************************************

'------------------------------------------------------------------------

Private Sub cmdFirst_Click()

'------------------------------------------------------------------------

If mobjDeptRst.RecordCount = 0 Then Exit Sub


DisplayDeptRecord

End Sub

'------------------------------------------------------------------------

Private Sub cmdNext_Click()

'------------------------------------------------------------------------


With mobjDeptRst

.MoveNext

If .EOF Then

Beep

.MoveLast



End If

End With

DisplayDeptRecord

End Sub

'------------------------------------------------------------------------

Private Sub cmdPrev_Click()

'------------------------------------------------------------------------


With mobjDeptRst

.MovePrevious

If .BOF Then

Beep

.MoveFirst

End If

End With

DisplayDeptRecord

End Sub

'------------------------------------------------------------------------

Private Sub cmdLast_Click()

'------------------------------------------------------------------------



DisplayDeptRecord

End Sub

'------------------------------------------------------------------------

Private Sub cmdAdd_Click()

'------------------------------------------------------------------------

ClearTheForm

mstrAction = "ADD"

ResetFormControls True, vbWhite

mblnChangeMade = False

If mobjDeptRst.RecordCount > 0 Then

mvntBookMark = mobjDeptRst.Bookmark

End If

mobjDeptRst.AddNew

txtDeptField(0).SetFocus

mblnOKToExit = False

End Sub



'------------------------------------------------------------------------

Private Sub cmdUpdate_Click()

'------------------------------------------------------------------------

If mobjDeptRst.RecordCount = 0 Then

MsgBox "There are no records currently on file to update.", _

vbInformation, "Update Record"

Exit Sub

End If

mstrAction = "UPDATE"




mobjDeptRst.Edit



End Sub

'------------------------------------------------------------------------

Private Sub cmdDelete_Click()

'------------------------------------------------------------------------

Dim objTempRst As Recordset

Dim intEmpCount As Integer


MsgBox "There are no records currently on file to delete.", _

vbInformation, "Delete Record"

Exit Sub

End If

If MsgBox("Are you sure you want to delete this record?", _

vbQuestion + vbYesNo + vbDefaultButton2, _

"Delete Record") = vbNo Then

Exit Sub

End If

' check for referential integrity violation ...



& "WHERE DeptNbr = " & mobjDeptRst!DeptNbr)

intEmpCount = objTempRst!EmpCount

objTempRst.Close

Set objTempRst = Nothing

If intEmpCount > 0 Then

MsgBox "This department record cannot be deleted because " _

& "it is in use by one or more employees.", _

vbExclamation, _

"Department Is In Use"

Exit Sub

End If

mobjDeptRst.Delete




ClearTheForm

Else

cmdNext_Click

End If

End Sub

'------------------------------------------------------------------------

Private Sub cmdSave_Click()

'------------------------------------------------------------------------


ValidateAllFields

If mblnValidationError Then Exit Sub

With mobjDeptRst

If mstrAction = "ADD" Then

!DeptNbr = txtDeptField(0).Text

End If

!DeptName = txtDeptField(1).Text

!Location = txtDeptField(2).Text

.Update

.Bookmark = .LastModified

End With

ResetFormControls False, vbButtonFace

mblnOKToExit = True

End Sub

'------------------------------------------------------------------------

Private Sub cmdUndo_Click()

'------------------------------------------------------------------------

If Not mblnChangeMade Then Exit Sub

If MsgBox("Do you want to abandon your changes to this record?", _

vbQuestion + vbYesNo, "Undo") = vbNo Then

Exit Sub

End If


ClearTheForm


Else

DisplayDeptRecord


End If


End Sub

'------------------------------------------------------------------------

Private Sub cmdCancel_Click()

'------------------------------------------------------------------------

If mblnChangeMade Then





Exit Sub

End If

End If


ClearTheForm

Else

mobjDeptRst.Bookmark = mvntBookMark

DisplayDeptRecord

End If


mblnOKToExit = True

End Sub

'------------------------------------------------------------------------

Private Sub cmdGoToDeptNbr_Click()

'------------------------------------------------------------------------

Dim strReqDeptNbr As String

Dim lngReqDeptNbr As Long

If mobjDeptRst.Index = "idxDeptName" Then

If MsgBox("This search will cause the record browsing " _

& "sequence to change to department number sequence. " _

& "Is that OK?", vbYesNo + vbQuestion, _

"Browse Sequence") = vbNo Then

Exit Sub

End If

End If

strReqDeptNbr = InputBox _

("Type in the Department # that you are looking for. ", _

"Go To Dept # ...")

If strReqDeptNbr = "" Then

' user clicked the Cancel button on the input box

' or did not enter anything

Exit Sub

End If

lngReqDeptNbr = Val(strReqDeptNbr)



mobjDeptRst.Seek "=", lngReqDeptNbr


MsgBox "Dept # " & lngReqDeptNbr & " could not be found.", _

vbExclamation, "Dept # Not Found"


Else

DisplayDeptRecord

End If

End Sub



'------------------------------------------------------------------------

Private Sub cmdGoToDeptName_Click()

'------------------------------------------------------------------------

Dim strReqDeptName As String

If mobjDeptRst.Index = "idxDeptNbrPK" Then


& "sequence to change to department name sequence. " _



Exit Sub

End If

End If

strReqDeptName = UCase$(InputBox _

("Type in the first several letters of the Department Name that you are

looking for. ", _

"Go To Dept # ..."))

If strReqDeptName = "" Then



Exit Sub

End If



mobjDeptRst.Seek ">=", strReqDeptName


MsgBox "Dept Name beginning '" & strReqDeptName & "' could not be

found.", _

vbExclamation, "Dept Not Found"


Else

DisplayDeptRecord

End If

End Sub

'------------------------------------------------------------------------

Private Sub cmdHelp_Click()

'------------------------------------------------------------------------

gintHelpFileNbr = 3


End Sub

'------------------------------------------------------------------------

Private Sub cmdExit_Click()

'------------------------------------------------------------------------

Unload Me

End Sub

'************************************************************************



'* *

'* PROGRAMMER-DEFINED *

'* (Non-Event) Procedures & Functions *

'* *

'************************************************************************

'------------------------------------------------------------------------

Private Sub DisplayDeptRecord()

'------------------------------------------------------------------------

Dim intX As Integer

With mobjDeptRst

txtDeptField(0).Text = !DeptNbr

txtDeptField(1).Text = !DeptName

txtDeptField(2).Text = !Location

End With

End Sub

'------------------------------------------------------------------------

Private Sub ResetFormControls(blnEnabledValue As Boolean, lngColor As

Long)

'------------------------------------------------------------------------

Dim intX As Integer

fraDeptData.Enabled = blnEnabledValue

For intX = 0 To 2

txtDeptField(intX).BackColor = lngColor

Next

If mstrAction = "UPDATE" Then

txtDeptField(0).Enabled = Not blnEnabledValue

End If

cmdSave.Enabled = blnEnabledValue

cmdUndo.Enabled = blnEnabledValue

cmdCancel.Enabled = blnEnabledValue

cmdFirst.Enabled = Not blnEnabledValue

cmdNext.Enabled = Not blnEnabledValue

cmdPrev.Enabled = Not blnEnabledValue

cmdLast.Enabled = Not blnEnabledValue

cmdAdd.Enabled = Not blnEnabledValue

cmdUpdate.Enabled = Not blnEnabledValue

cmdDelete.Enabled = Not blnEnabledValue

cmdExit.Enabled = Not blnEnabledValue


End Sub

'------------------------------------------------------------------------

Private Sub ClearTheForm()

'------------------------------------------------------------------------



Dim intX As Integer

For intX = 0 To 2

txtDeptField(intX).Text = ""

Next

End Sub

'------------------------------------------------------------------------

Private Sub ValidateAllFields()

'------------------------------------------------------------------------

Dim intX As Integer


For intX = 0 To 2

If Not DeptFieldIsValid(intX) Then


Beep

txtDeptField(intX).SetFocus

End If

If intX < 2 Then

If mintCurrTabIndex = txtDeptField(intX + 1).TabIndex _

Or mblnValidationError Then

Exit For

End If

End If

Next

End Sub

'------------------------------------------------------------------------

Private Function DeptFieldIsValid(intFieldIndex As Integer) As Boolean

'------------------------------------------------------------------------

Dim strMBMsg As String

Dim strMBTitle As String

Dim blnItsValid As Boolean

blnItsValid = True

Select Case intFieldIndex

Case 0

'*** Department Number


' validation checks for the department number are only

' applicable when adding, not updating a record ...

If txtDeptField(0).Text = "" Then

strMBMsg = "Department Number must be entered"

strMBTitle = "Department Number"

blnItsValid = False

ElseIf DeptExists(txtDeptField(0).Text) Then

strMBMsg = "Department '" & txtDeptField(0).Text _

& "' already exists."

strMBTitle = "Department Already Exists"

blnItsValid = False

End If

End If



Case 1

'*** Department Name


strMBMsg = "Department Name must not be blank"

strMBTitle = "Department Name"

blnItsValid = False

End If

Case Else

'*** Location


strMBMsg = "Location must be entered"

strMBTitle = "Location"

blnItsValid = False

End If

End Select

If blnItsValid Then

DeptFieldIsValid = True

Else

DeptFieldIsValid = False

MsgBox strMBMsg, vbExclamation, strMBTitle

End If

End Function

'------------------------------------------------------------------------

Private Function DeptExists(strDeptNbr As String) As Boolean

'------------------------------------------------------------------------


Dim intDeptCount As Integer


("SELECT COUNT(*) AS DeptCount FROM DeptMast " _

& "WHERE DeptNbr = " & strDeptNbr)

intDeptCount = objTempRst!DeptCount

objTempRst.Close


DeptExists = IIf(intDeptCount = 0, False, True)

End Function

The Job Maintenance Form (frmJobMaint):

The Job Maintenance form, named "frmJobMaint", is shown below. This form enables the user to performmaintenance on the JobMast table. The techniques used on this form are very similar to those used infrmDeptMaint. The differences are that there a few more fields on this form and the JobNbr field is anAutoNumber field.



Code for frmJobMaint:

Option Explicit

'************************************************************************

'************************************************************************

'** **


'** **

'************************************************************************

'************************************************************************

Private mobjJobRst As Recordset






Private mintCurrTabIndex As Integer

'************************************************************************

'************************************************************************

'** **


'** **

'************************************************************************

'************************************************************************

'************************************************************************

'* *




'* *

'************************************************************************

'------------------------------------------------------------------------


'------------------------------------------------------------------------

CenterForm Me

OpenEmpDatabase

Set mobjJobRst = gobjEmpDB.OpenRecordset("JobMast", dbOpenTable)

mblnOKToExit = True

cmdFirst_Click

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


cmdHelp_Click

End If

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------





Cancel = 1

Exit Sub

End If

CloseEmpDatabase

End Sub

'************************************************************************

'* JOB FIELDS *

'************************************************************************

'------------------------------------------------------------------------

Private Sub txtJobField_GotFocus(Index As Integer)

'------------------------------------------------------------------------

SelectTextBoxText txtJobField(Index)

If Index > 0 Then



mintCurrTabIndex = txtJobField(Index).TabIndex

ValidateAllFields

End If

End Sub

'------------------------------------------------------------------------

Private Sub txtJobField_KeyPress(Index As Integer, KeyAscii As Integer)

'------------------------------------------------------------------------


If Index > 0 Then

' rate field - allow only digits and decimal point

KeyAscii = ValidKey(KeyAscii, gstrNUMERIC_DIGITS & ".")

' if text already has a decimal point, do not allow another ...

If Chr$(KeyAscii) = "." And InStr(txtJobField(Index).Text, ".") > 0 Then

KeyAscii = 0

End If

Else

' job description - force uppercase

KeyAscii = ConvertUpper(KeyAscii)

End If

End Sub

'------------------------------------------------------------------------

Private Sub txtJobField_Change(Index As Integer)

'------------------------------------------------------------------------


If Index < 3 Then

TabToNextTextBox txtJobField(Index), txtJobField(Index + 1)

End If

End Sub

'------------------------------------------------------------------------

Private Sub txtJobField_LostFocus(Index As Integer)

'------------------------------------------------------------------------

If Index > 0 Then

txtJobField(Index).Text = Format$(txtJobField(Index).Text, "Fixed")

End If

End Sub

'------------------------------------------------------------------------

Private Sub txtJobField_Validate(Index As Integer, Cancel As Boolean)

'------------------------------------------------------------------------

' this event is only being used for the last field on the form ...

If Index = 3 Then


ValidateAllFields

If mblnValidationError Then

Cancel = True



End If

End If

End Sub

'************************************************************************

'* *

'* COMMAND BUTTON *


'* *

'************************************************************************

'------------------------------------------------------------------------


'------------------------------------------------------------------------

If mobjJobRst.RecordCount = 0 Then Exit Sub

mobjJobRst.MoveFirst

DisplayJobRecord

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


With mobjJobRst

.MoveNext

If .EOF Then

Beep

.MoveLast

End If

End With

DisplayJobRecord

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


With mobjJobRst

.MovePrevious

If .BOF Then

Beep

.MoveFirst

End If

End With



DisplayJobRecord

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


mobjJobRst.MoveLast

DisplayJobRecord

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

ClearTheForm



If mobjJobRst.RecordCount > 0 Then

mvntBookMark = mobjJobRst.Bookmark

End If

mobjJobRst.AddNew

'display the Access(JET)-generated autonumber ...

lblJobNbr.Caption = mobjJobRst!JobNbr

mstrAction = "ADD"

txtJobField(0).SetFocus


End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

If mobjJobRst.RecordCount = 0 Then



Exit Sub

End If




mobjJobRst.Edit






End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


Dim intEmpCount As Integer




Exit Sub

End If




Exit Sub

End If

' check for referential integrity violation ...



& "WHERE JobNbr = " & mobjJobRst!JobNbr)

intEmpCount = objTempRst!EmpCount

objTempRst.Close


If intEmpCount > 0 Then

MsgBox "This job record cannot be deleted because " _

& "it is in use by one or more employees.", _

vbExclamation, "Job Is In Use"

Exit Sub

End If

mobjJobRst.Delete


ClearTheForm

Else

cmdNext_Click

End If

End Sub

'------------------------------------------------------------------------

Private Sub cmdGoToJobNbr_Click()

'------------------------------------------------------------------------

Dim strReqJobNbr As String

Dim lngReqJobNbr As Long

If mobjJobRst.Index = "idxJobName" Then


& "sequence to change to job number sequence. " _





Exit Sub

End If

End If

strReqJobNbr = InputBox _

("Type in the Job # that you are looking for. ", _

"Go To Job # ...")

If strReqJobNbr = "" Then



Exit Sub

End If

lngReqJobNbr = Val(strReqJobNbr)


mobjJobRst.Index = "idxJobNbrPK"

mobjJobRst.Seek "=", lngReqJobNbr

If mobjJobRst.NoMatch Then

MsgBox "Job # " & lngReqJobNbr & " could not be found.", _

vbExclamation, "Job # Not Found"

mobjJobRst.Bookmark = mvntBookMark

Else

DisplayJobRecord

End If

End Sub

'------------------------------------------------------------------------

Private Sub cmdGoToJobTitle_Click()

'------------------------------------------------------------------------

Dim strReqJobTitle As String

If mobjJobRst.Index = "idxJobNbrPK" Then


& "sequence to change to job title sequence. " _



Exit Sub

End If

End If

strReqJobTitle = UCase$(InputBox _

("Type in the first several letters of the Job title that you are looking

for. ", _

"Go To Job # ..."))

If strReqJobTitle = "" Then



Exit Sub

End If


mobjJobRst.Index = "idxJobtitle"

mobjJobRst.Seek ">=", strReqJobTitle

If mobjJobRst.NoMatch Then



MsgBox "Job Title beginning '" & strReqJobTitle & "' could not be

found.", _

vbExclamation, "Job Not Found"


Else

DisplayJobRecord

End If

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


ValidateAllFields


With mobjJobRst

!JobTitle = txtJobField(0).Text

!MinRate = Val(txtJobField(1).Text)

!AvgRate = Val(txtJobField(2).Text)

!MaxRate = Val(txtJobField(3).Text)

.Update


End With


mblnOKToExit = True

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------




Exit Sub

End If


ClearTheForm

lblJobNbr.Caption = mobjJobRst!JobNbr

Else

DisplayJobRecord

End If



End Sub

'------------------------------------------------------------------------




'------------------------------------------------------------------------




Exit Sub

End If

End If


ClearTheForm

Else


DisplayJobRecord

End If


mblnOKToExit = True

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

gintHelpFileNbr = 4


End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

Unload Me

End Sub

'************************************************************************

'* *



'* *

'************************************************************************

'------------------------------------------------------------------------

Private Sub DisplayJobRecord()

'------------------------------------------------------------------------

With mobjJobRst

lblJobNbr.Caption = !JobNbr

txtJobField(0).Text = !JobTitle

txtJobField(1).Text = Format$(!MinRate, "Fixed")

txtJobField(2).Text = Format$(!AvgRate, "Fixed")

txtJobField(3).Text = Format$(!MaxRate, "Fixed")



End With

End Sub

'------------------------------------------------------------------------

Private Sub ResetFormControls(blnEnabledValue As Boolean, lngColor As

Long)

'------------------------------------------------------------------------

Dim intX As Integer

fraJobData.Enabled = blnEnabledValue

For intX = 0 To 3

txtJobField(intX).BackColor = lngColor

Next

cmdSave.Enabled = blnEnabledValue

cmdUndo.Enabled = blnEnabledValue

cmdCancel.Enabled = blnEnabledValue

cmdGoToJobNbr.Enabled = Not blnEnabledValue

cmdGoToJobTitle.Enabled = Not blnEnabledValue

cmdFirst.Enabled = Not blnEnabledValue

cmdNext.Enabled = Not blnEnabledValue

cmdPrev.Enabled = Not blnEnabledValue

cmdLast.Enabled = Not blnEnabledValue

cmdAdd.Enabled = Not blnEnabledValue

cmdUpdate.Enabled = Not blnEnabledValue

cmdDelete.Enabled = Not blnEnabledValue

cmdExit.Enabled = Not blnEnabledValue


End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

Dim intX As Integer

lblJobNbr = ""

For intX = 0 To 3

txtJobField(intX).Text = ""

Next

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

Dim intX As Integer


For intX = 0 To 3

If Not JobFieldIsValid(intX) Then


Beep



txtJobField(intX).SetFocus

End If

If intX < 3 Then

If mintCurrTabIndex = txtJobField(intX + 1).TabIndex _

Or mblnValidationError Then

Exit For

End If

End If

Next

End Sub

'------------------------------------------------------------------------

Private Function JobFieldIsValid(intFieldIndex As Integer) As Boolean

'------------------------------------------------------------------------

Dim strMBMsg As String

Dim strMBTitle As String

Dim blnItsValid As Boolean

blnItsValid = True

Select Case intFieldIndex

Case 0

'*** Job Title

If txtJobField(0).Text = "" Then

strMBMsg = "Job Title must not be blank"

strMBTitle = "Job Title"

blnItsValid = False

End If

Case 1

'*** Minimum Rate

If Val(txtJobField(1).Text) <= 0 Then

strMBMsg = "Minimum Rate must be greater than zero."

strMBTitle = "Minimum Rate"

blnItsValid = False

End If

Case 2

'*** Average Rate


strMBMsg = "Average Rate must be greater than zero."

strMBTitle = "Average Rate"

blnItsValid = False

ElseIf Val(txtJobField(2).Text) < Val(txtJobField(1).Text) Then

strMBMsg _

= "Average Rate must be greater than or equal to the Minimum Rate."

strMBTitle = "Average Rate"

blnItsValid = False

End If

Case 3

'*** Maximum Rate


strMBMsg = "Maximum Rate must be greater than zero."

strMBTitle = "Maximum Rate"

blnItsValid = False



ElseIf Val(txtJobField(3).Text) < Val(txtJobField(2).Text) Then

strMBMsg _

= "Maximum Rate must be greater than or equal to the Average Rate."

strMBTitle = "Maxiumum Rate"

blnItsValid = False

End If

End Select

If blnItsValid Then

JobFieldIsValid = True

Else

JobFieldIsValid = False

MsgBox strMBMsg, vbExclamation, strMBTitle

End If

End Function

The Employee Maintenance Form (frmEmpMaint):

The Employee Maintenance form, named "frmEmpMaint", is shown below. This form enables the user toperform maintenance on the EmpMast table. This is the form that the user would probably interact most within this application; it could be considered the "main" form. The techniques used on this form are very similarto those used on the frmDeptMaint and frmJobMaint forms, although more is going on in this form.

Following is a list of items applicable to this form: ℜ• This form employs combo boxes for the user to set the employee's department, job, and hourly rate.

The department and job combo boxes are the "drop-down list" type, so the user can only choose one ofthe available items from the lists. The hourly rate combo box gives the user a choice of selecting theminimum, average, or maximum rate for the job, or they can override it by keying in their own value in the



textbox portion of that combo box. ℜ• This form introduces the DTPicker (Date/Time Picker) control. This control was introduced with VB6.

It enables the user to either key in a date (the control provides automatic date validation) or allows theuser to select a date from a drop-down calendar. The date that the user keys in or selects is stored in theDTPicker control's Value property.

The DTPicker will become available inyour toolbox when you include MicrosoftWindows Common Controls â€“ 2

6.0 (SPx) from Project ��Components as shown below:

The DTPicker appears inyour toolbox as showncircled below:

The DTPicker in action:

ℜ• Due to the variety of controls that represent the employee fields, a control array of textboxes is not

used. The necessary validation is performed on the individual fields using methods previouslydescribed.

ℜ• This form has a Search area that employs the Find methods of the Recordset object, as described

below.

The Find Methods

The Recordset object has methods FindFirst, FindLast, FindNext, and FindPrevious. You can use theseto search for a particular record in the Recordset. The syntax is

objSomeRecordset.FindFirst criteria

where criteria is a string item consisting of a field name, a relational (comparison) operator, and a value. It is



essentially the same as a SQL WHERE clause without the word WHERE. The comparison operators thatcan be used are =, >, <, >=, <=, <>, Like, Between, and In. The value on the right-hand side of thecomparison operator must conform to the following rules:string values must be enclosed in single quotesnumeric values are not enclosed in quotesdate values must be enclosed in #'s (pound signs)If the criteria is expressed in a literal string, that string must be enclosed in double quotes. Typically, you must use VB's string-

handling functions (especially the "&" for concatenation) to get the desired results.

Examples:

objSomeRecordset.FindFirst "ISBN = '123-456-789-0' "

objSomeRecordset.FindNext "Amount > 100"

objSomeRecordset.FindNext "DateOfBirth < #1/1/1950#"

objSomeRecordset.FindNext "Amount > " & txtAmount.Text

objSomeRecordset.FindNext "FirstName = '" & txtName.Text & "'"

The next example assumes that the variable dtmBirthDay is of the Date data type: objSomeRecordset.FindNext _

"DateOfBirth < #" & Format$(dtmBirthDay, "mm/dd/yyyy") & "#"

Additional Notes:ℜ• If the name of the field in the database table has spaces in its name, you must put square brackets

around the field name, as in the following example:

objSomeRecordset.FindFirst "[Pay Rate] > 30000"

ℜ• For string values, if there is the possibility that the search string will contain an apostrophe, an extra measure should be

taken to "double" the apostrophes in the string â€“ otherwise, the apostrophe embedded in the string will be interpreted as

the end of the string and a syntax error will most likely result. The easiest way to provide this "insurance" against embedded

apostrophes is to use the Replace$ function on the string in question to replace any occurrences of a single apostrophe with

two apostrophes:

objSomeRecordset.FindFirst _

"ProductName = '" & Replace$(strSearchText, "'", "''") & "'"

For example, if strSearchText contained "Chef Anton's Cajun Gumbo", the criteria in the abovestatement would evaluate to

ProductName = 'Chef Anton''s Cajun Gumbo'

and the double apostrophe in "Anton''s" would be correctly interpreted by the SQL parser as a singleapostrophe. In this particular example, if the Replace function was NOT used (i.e., you simply coded"ProductName = '" & strSearchText & "'"

for the criteria, the result would beProductName = 'Chef Anton's Cajun Gumbo'

which would result in an error: the SQL parser would interpret the criteria to be "Chef Anton" withextraneous characters ("s Cajun Gumbo") at the end.

As discussed earlier, the Recordset object has a NoMatch property, which can be used after a Seek(discussed earlier) or after one of the Find methods. The NoMatch property set to False to begin with. If you



use a Find method and a record is not found, then the NoMatch property is set to True. You should use thisproperty to determine whether or not a record was found. If a match is found, NoMatch will be set to True,and the found record becomes the current record. Code for frmEmpMaint:

Option Explicit

'************************************************************************

'************************************************************************

'** **


'** **

'************************************************************************

'************************************************************************

Private mobjEmpRst As Recordset




Private intCurrTabIndex As Integer


Private mblnActivated As Boolean


'************************************************************************

'************************************************************************

'** **


'** **

'************************************************************************

'************************************************************************

'************************************************************************

'* *


'* *

'************************************************************************

'------------------------------------------------------------------------

Private Sub Form_Activate()

'------------------------------------------------------------------------

If mblnActivated Then Exit Sub Else mblnActivated = True

CenterForm Me

OpenEmpDatabase

If gobjEmpDB.TableDefs("DeptMast").RecordCount = 0 Then

MsgBox "There are no records in the DeptMast table. " _

& "At least one record must be present in the DeptMast " _

& "table in order for Employee maintenance to take place. ", _

vbExclamation, "No DeptMast Records"

Unload Me



Exit Sub

End If

If gobjEmpDB.TableDefs("JobMast").RecordCount = 0 Then

MsgBox "There are no records in the JobMast table. " _

& "At least one record must be present in the JobMast " _

& "table in order for Employee maintenance to take place. ", _

vbExclamation, "No JobMast Records"

Unload Me

Exit Sub

End If

Set mobjEmpRst = gobjEmpDB.OpenRecordset("EmpMast", dbOpenDynaset)

LoadDeptCombo

LoadJobCombo

cboField.ListIndex = 0

cboRelOp.ListIndex = 0

mblnOKToExit = True

cmdFirst_Click

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


cmdHelp_Click

End If

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------





Cancel = 1

Exit Sub

End If

mobjEmpRst.Close

Set mobjEmpRst = Nothing

CloseEmpDatabase

End Sub

'************************************************************************

'* EMPLOYEE FIELDS *

'* TextPlus and Comob Box Event Procedures *

'************************************************************************



'------------------------------------------------------------------------

Private Sub txtEmpFirst_GotFocus()

'------------------------------------------------------------------------

SelectTextBoxText txtEmpFirst

End Sub

'------------------------------------------------------------------------

Private Sub txtEmpFirst_KeyPress(KeyAscii As Integer)

'------------------------------------------------------------------------


KeyAscii = ValidKey(ConvertUpper(KeyAscii), gstrUPPER_ALPHA_PLUS)

End Sub

'------------------------------------------------------------------------

Private Sub txtEmpFirst_Change()

'------------------------------------------------------------------------


End Sub

'------------------------------------------------------------------------

Private Sub txtEmpLast_GotFocus()

'------------------------------------------------------------------------

SelectTextBoxText txtEmpLast

intCurrTabIndex = txtEmpLast.TabIndex

ValidateAllFields

End Sub

'------------------------------------------------------------------------

Private Sub txtEmpLast_KeyPress(KeyAscii As Integer)

'------------------------------------------------------------------------


KeyAscii = ValidKey(ConvertUpper(KeyAscii), gstrUPPER_ALPHA_PLUS)

End Sub

'------------------------------------------------------------------------

Private Sub txtEmpLast_Change()

'------------------------------------------------------------------------


End Sub

'------------------------------------------------------------------------

Private Sub cboDept_GotFocus()

'------------------------------------------------------------------------

intCurrTabIndex = cboDept.TabIndex

ValidateAllFields

End Sub

'------------------------------------------------------------------------

Private Sub cboDept_Click()



'------------------------------------------------------------------------


End Sub

'------------------------------------------------------------------------

Private Sub cboJob_GotFocus()

'------------------------------------------------------------------------

intCurrTabIndex = cboJob.TabIndex

ValidateAllFields

End Sub

'------------------------------------------------------------------------

Private Sub cboJob_Click()

'------------------------------------------------------------------------



("SELECT MinRate, AvgRate, MaxRate FROM JobMast " _

& "WHERE JobNbr = " & cboJob.ItemData(cboJob.ListIndex))

'Note: The first record (and only record in this case) is

'always current when a recordset is open - therefore, it is

'not necessary to do "objTempRst.MoveFirst"

'Load the Hourly Rate combo box with the min, avg, and max rates

'for the selected job, and pre-select the avg rate ...

With cboHrlyRate

.Clear

.AddItem Format$(objTempRst!MinRate, "Fixed")

.AddItem Format$(objTempRst!AvgRate, "Fixed")

.AddItem Format$(objTempRst!MaxRate, "Fixed")

.ListIndex = 1

End With



End Sub

'------------------------------------------------------------------------

Private Sub dtpHireDate_GotFocus()

'------------------------------------------------------------------------

intCurrTabIndex = dtpHireDate.TabIndex

ValidateAllFields

End Sub

'------------------------------------------------------------------------

Private Sub dtpHireDate_Change()

'------------------------------------------------------------------------


End Sub

'------------------------------------------------------------------------

Private Sub cboHrlyRate_GotFocus()

'------------------------------------------------------------------------



intCurrTabIndex = cboHrlyRate.TabIndex

ValidateAllFields

End Sub

'------------------------------------------------------------------------

Private Sub cboHrlyRate_Change()

'------------------------------------------------------------------------


End Sub

'------------------------------------------------------------------------

Private Sub cboHrlyRate_Click()

'------------------------------------------------------------------------


End Sub

'------------------------------------------------------------------------

Private Sub cboHrlyRate_LostFocus()

'------------------------------------------------------------------------

cboHrlyRate.Text = Format$(cboHrlyRate.Text, "Fixed")

End Sub

'------------------------------------------------------------------------

Private Sub txtSchedHrs_GotFocus()

'------------------------------------------------------------------------

SelectTextBoxText txtSchedHrs

intCurrTabIndex = txtSchedHrs.TabIndex

ValidateAllFields

End Sub

'------------------------------------------------------------------------

Private Sub txtSchedHrs_Change()

'------------------------------------------------------------------------


End Sub

'------------------------------------------------------------------------

Private Sub txtSchedHrs_KeyPress(KeyAscii As Integer)

'------------------------------------------------------------------------


KeyAscii = ValidKey(KeyAscii, gstrNUMERIC_DIGITS & ".")

' if text already has a decimal point, do not allow another ...

If Chr$(KeyAscii) = "." And InStr(txtSchedHrs.Text, ".") > 0 Then

KeyAscii = 0

End If

End Sub

'------------------------------------------------------------------------

Private Sub txtSchedHrs_Validate(Cancel As Boolean)

'------------------------------------------------------------------------

intCurrTabIndex = -1



ValidateAllFields

If mblnValidationError Then Cancel = True

End Sub

'------------------------------------------------------------------------

Private Sub txtSchedHrs_LostFocus()

'------------------------------------------------------------------------

txtSchedHrs.Text = Format$(txtSchedHrs.Text, "Fixed")

End Sub

'------------------------------------------------------------------------

Private Sub txtCriteria_GotFocus()

'------------------------------------------------------------------------

SelectTextBoxText txtCriteria

End Sub

'************************************************************************

'* *

'* COMMAND BUTTON *


'* *

'************************************************************************

'------------------------------------------------------------------------


'------------------------------------------------------------------------

If mobjEmpRst.RecordCount = 0 Then Exit Sub

mobjEmpRst.MoveFirst

DisplayEmpRecord

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


With mobjEmpRst

.MoveNext

If .EOF Then

Beep

.MoveLast

End If

End With

DisplayEmpRecord

End Sub

'------------------------------------------------------------------------




'------------------------------------------------------------------------


With mobjEmpRst

.MovePrevious

If .BOF Then

Beep

.MoveFirst

End If

End With

DisplayEmpRecord

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


mobjEmpRst.MoveLast

DisplayEmpRecord

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

ClearTheForm



If mobjEmpRst.RecordCount > 0 Then

mvntBookMark = mobjEmpRst.Bookmark

End If

mobjEmpRst.AddNew

'display the Access(JET)-generated autonumber ...

lblEmpNbr.Caption = mobjEmpRst!EmpNbr

mstrAction = "ADD"

txtEmpFirst.SetFocus


End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

If mobjEmpRst.RecordCount = 0 Then





Exit Sub

End If




mobjEmpRst.Edit




End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------




Exit Sub

End If




Exit Sub

End If

mobjEmpRst.Delete


ClearTheForm

Else

cmdNext_Click

End If

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

gintHelpFileNbr = 2


End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

Unload Me

End Sub



'------------------------------------------------------------------------


'------------------------------------------------------------------------

intCurrTabIndex = -1

ValidateAllFields


With mobjEmpRst

!EmpFirst = txtEmpFirst.Text

!EmpLast = txtEmpLast.Text

!DeptNbr = cboDept.ItemData(cboDept.ListIndex)

!JobNbr = cboJob.ItemData(cboJob.ListIndex)

!HireDate = dtpHireDate.Value

!HrlyRate = Val(cboHrlyRate.Text)

!SchedHrs = Val(txtSchedHrs.Text)

.Update


End With


mblnOKToExit = True

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------




Exit Sub

End If


ClearTheForm

Else

DisplayEmpRecord

End If



End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------




Exit Sub

End If

End If




ClearTheForm

Else

mobjEmpRst.Bookmark = mvntBookMark

DisplayEmpRecord

End If


mblnOKToExit = True

End Sub

'************************************************************************

'* *

'* "SEARCH" FRAME CONTROLS *


'* *

'************************************************************************

'------------------------------------------------------------------------

Private Sub cboRelOp_Click()

'------------------------------------------------------------------------

If cboRelOp.Text = "Like" Then

If cboField.Text = "First Name" Or cboField.Text = "Last Name" Then

' it's OK

Else

MsgBox "Comparison operator 'Like' may only be used with the " _

& "fields 'First Name' or 'Last Name'.", vbInformation, _

"Invalid Comparison Operator"

cboRelOp.SetFocus

End If

End If

End Sub

'------------------------------------------------------------------------

Private Sub cmdFind_Click(Index As Integer)

'------------------------------------------------------------------------

Dim strFindString As String

' perform this validation before moving on ...

If cboField.Text = "Hire Date" Then

If IsDate(txtCriteria.Text) Then

txtCriteria.Text _

= Format$(CDate(txtCriteria.Text), "m/d/yyyy")

Else

MsgBox "Criteria for 'Hire Date' is not valid.", _

vbExclamation, "Invalid Criteria"

txtCriteria.SetFocus

Exit Sub

End If

End If



'save current rec's bookmark in case of NoMatch ...


'start building the criteria string for the Find method with the field

'name of the desired database field, based on the user's cboField

selection ...

Select Case cboField.Text

Case "Emp #": strFindString = "EmpNbr"

Case "First Name": strFindString = "EmpFirst"

Case "Last Name": strFindString = "EmpLast"

Case "Dept #": strFindString = "DeptNbr"

Case "Job #": strFindString = "JobNbr"

Case "Hire Date": strFindString = "HireDate"

Case "Hourly Rate": strFindString = "HrlyRate"

Case "Sched. Wkly Hrs": strFindString = "SchedHrs"

End Select

'append the selected relational operator to the find string ...

strFindString = strFindString & " " & cboRelOp.Text & " "

'finally, append the value to search for to the find string ...

If cboField.Text = "First Name" _

Or cboField.Text = "Last Name" Then

strFindString = strFindString _

& Chr$(34) & txtCriteria.Text & Chr$(34)

ElseIf cboField.Text = "Hire Date" Then

strFindString = strFindString _

& "#" & txtCriteria.Text & "#"

Else

strFindString = strFindString & Val(txtCriteria.Text)

End If

' call the appropriate Find method, depending upon which

' button the user clicked ...

Select Case Index

Case 0: mobjEmpRst.FindFirst strFindString

Case 1: mobjEmpRst.FindPrevious strFindString

Case 2: mobjEmpRst.FindNext strFindString

Case 3: mobjEmpRst.FindLast strFindString

End Select

' deal with the match results ...

If mobjEmpRst.NoMatch Then

MsgBox "No (other) records matched your search criteria.", _

vbInformation, "Not Found"

mobjEmpRst.Bookmark = mvntBookMark

Else

' the found record is now the current record ...

DisplayEmpRecord

End If

End Sub

'************************************************************************

'* *





'* *

'************************************************************************

'------------------------------------------------------------------------

Private Sub LoadDeptCombo()

'------------------------------------------------------------------------


Set objTempRst = gobjEmpDB.OpenRecordset("DeptMast", dbOpenTable)

With objTempRst

.MoveFirst

Do Until .EOF

cboDept.AddItem !DeptName & " (" & !DeptNbr & ")"

cboDept.ItemData(cboDept.NewIndex) = !DeptNbr

.MoveNext

Loop

.Close

End With


End Sub

'------------------------------------------------------------------------

Private Sub LoadJobCombo()

'------------------------------------------------------------------------


Set objTempRst = gobjEmpDB.OpenRecordset("JobMast", dbOpenTable)

With objTempRst

.MoveFirst

Do Until .EOF

cboJob.AddItem !JobTitle & " (" & !JobNbr & ")"

cboJob.ItemData(cboJob.NewIndex) = !JobNbr

.MoveNext

Loop

.Close

End With


End Sub

'------------------------------------------------------------------------

Private Sub DisplayEmpRecord()

'------------------------------------------------------------------------

Dim intX As Integer

With mobjEmpRst

lblEmpNbr = !EmpNbr

txtEmpFirst.Text = !EmpFirst



txtEmpLast.Text = !EmpLast

For intX = 0 To cboDept.ListCount - 1

If !DeptNbr = cboDept.ItemData(intX) Then

cboDept.ListIndex = intX

Exit For

End If

Next

For intX = 0 To cboJob.ListCount - 1

If !JobNbr = cboJob.ItemData(intX) Then

cboJob.ListIndex = intX ' will invoke cboJob_Click event

Exit For

End If

Next

lblHireDate = Format$(!HireDate, "m/d/yyyy")

dtpHireDate.Value = !HireDate

cboHrlyRate.Text = Format$(!HrlyRate, "#0.00")

txtSchedHrs.Text = Format$(!SchedHrs, "#0.00")

End With

End Sub

'------------------------------------------------------------------------

Private Sub ResetFormControls(pblnEnabledValue As Boolean, lngColor As

Long)

'------------------------------------------------------------------------

Dim intX As Integer

fraEmpInfoInner.Enabled = pblnEnabledValue

txtEmpFirst.BackColor = lngColor

txtEmpLast.BackColor = lngColor

cboDept.BackColor = lngColor

cboJob.BackColor = lngColor

If pblnEnabledValue = True Then

dtpHireDate.Value = CDate(lblHireDate)

Else

lblHireDate = Format$(dtpHireDate.Value, "m/d/yyyy")

End If

dtpHireDate.Visible = pblnEnabledValue

lblHireDate.Visible = Not pblnEnabledValue

cboHrlyRate.BackColor = lngColor

txtSchedHrs.BackColor = lngColor

cmdSave.Enabled = pblnEnabledValue

cmdUndo.Enabled = pblnEnabledValue

cmdCancel.Enabled = pblnEnabledValue

cmdFirst.Enabled = Not pblnEnabledValue

cmdNext.Enabled = Not pblnEnabledValue

cmdPrev.Enabled = Not pblnEnabledValue

cmdLast.Enabled = Not pblnEnabledValue

cmdAdd.Enabled = Not pblnEnabledValue

cmdUpdate.Enabled = Not pblnEnabledValue



cmdDelete.Enabled = Not pblnEnabledValue

cmdExit.Enabled = Not pblnEnabledValue

fraSearchInner.Enabled = Not pblnEnabledValue

cboField.BackColor = IIf(lngColor = vbWhite, vbButtonFace, vbWhite)

cboRelOp.BackColor = IIf(lngColor = vbWhite, vbButtonFace, vbWhite)

txtCriteria.BackColor = IIf(lngColor = vbWhite, vbButtonFace, vbWhite)

For intX = 0 To 3

cmdFind(intX).Enabled = Not pblnEnabledValue

Next


End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

txtEmpFirst.Text = ""

txtEmpLast.Text = ""

cboDept.ListIndex = 0 'default to first Dept in the list

cboJob.ListIndex = 0 'default to first Job in the list

lblHireDate = Format$(Date, "m/d/yyyy") 'default to today's date

cboHrlyRate.ListIndex = 1 'default to the average rate

txtSchedHrs.Text = "40.00" 'default to 40 hrs per week

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------


'*** First Name

If txtEmpFirst.Text = "" Then

MsgBox "First Name must not be blank", _

vbExclamation, "First Name"


Beep


End If

If intCurrTabIndex = txtEmpLast.TabIndex Or mblnValidationError Then

Exit Sub

End If

'*** Last Name

If txtEmpLast.Text = "" Then

MsgBox "Last Name must not be blank", _

vbExclamation, "Last Name"


Beep

txtEmpLast.SetFocus

End If

If intCurrTabIndex = cboDept.TabIndex Or mblnValidationError Then



Exit Sub

End If

'*** Department

' (no validation logic needed)

If intCurrTabIndex = cboJob.TabIndex Or mblnValidationError Then

Exit Sub

End If

'*** Job


If intCurrTabIndex = dtpHireDate.TabIndex Or mblnValidationError Then

Exit Sub

End If

'*** Hire Date


If intCurrTabIndex = cboHrlyRate.TabIndex Or mblnValidationError Then

Exit Sub

End If

'*** Hourly Rate

If cboHrlyRate.Text = "" Then

MsgBox "Hourly Rate must be entered.", _

vbExclamation, "Hourly Rate"


Beep

cboHrlyRate.SetFocus

ElseIf Not IsNumeric(cboHrlyRate.Text) Then

MsgBox "Hourly Rate must be numeric.", _



Beep


ElseIf Val(cboHrlyRate.Text) <= 0 Then

MsgBox "Hourly Rate must be greater than zero.", _



Beep


End If

If intCurrTabIndex = txtSchedHrs.TabIndex Or mblnValidationError Then

Exit Sub

End If

'*** Scheduled Hours

If txtSchedHrs.Text = "" Then

MsgBox "Hours must be entered.", _

vbExclamation, "Hours"


Beep

txtSchedHrs.SetFocus

ElseIf Val(txtSchedHrs.Text) <= 0 Then



MsgBox "Hours must be greater than zero.", _

vbExclamation, "Hours"


Beep

txtSchedHrs.SetFocus

End If

End Sub

The Report Menu Screen (frmReportMenu)

The Report Menu form, named "frmReportMenu", is shown below. This form enables the user print either ofthe two available reports created for this application with Crystal Reports. This is the exact same form thatwas used in the Crystal Reports demo presents a couple of articles back. Refer to that article for anexplanation of this form and the corresponding code.

Code for frmReportMenu

Option Explicit

'------------------------------------------------------------------------


'------------------------------------------------------------------------

CenterForm Me

End Sub

'------------------------------------------------------------------------

Private Sub cmdOK_Click()

'------------------------------------------------------------------------

On Error GoTo cmdOK_Click_Error

Dim strReportName As String



Dim intReportDestination As Integer

If optReport(0).Value = True Then

strReportName = "SALDEPT.RPT"

Else

strReportName = "SALJOB.RPT"

End If

If optDestination(0).Value = True Then

intReportDestination = crptToWindow

Else

intReportDestination = crptToPrinter

End If

With rptAnnSalExp

.ReportFileName = GetAppPath() & strReportName

.DataFiles(0) = GetAppPath() & "EMPLOYEE.MDB"

.Destination = intReportDestination

.Action = 1 ' 1 = "Run the Report"

End With

Exit Sub

cmdOK_Click_Error:

MsgBox "The following error has occurred:" & vbNewLine _

& Err.Number & " - " & Err.Description, _

vbCritical, _

"cmdOK_Click"

End Sub

'------------------------------------------------------------------------


'------------------------------------------------------------------------

Unload Me

End Sub

Download the project files for this sample application here.

Similar links



Amazing things you can do with the Listbox control

Database Access with RDO (Remote Data Objects)

Database Access with the Data Control

Using ADO and the ListView control

VB6 Animated Charts (With FusionCharts)

VB6 Downloads

Access Security

Using Jet Data Access Objects

Optimizing Database Applications

Database Design

115661 reads

Fri, 06/11/2010 - 05:38 — nasry (not verified)

Wed, 06/09/2010 - 00:47 — Edson (not verified)

Fri, 03/19/2010 - 02:20 — Susanta Kumar Rath (not verified)

Wed, 03/17/2010 - 02:21 — Emberdust (not verified)

Wed, 01/20/2010 - 08:34 — Jaffery (not verified)

i want to know how to do a

i want to know how to do a program in vb6.0 using microsoft windows common controls 6.0(sp6),microsoft DAO 6.0

object library, help me i want to submit my project before 17th of june.

reply

Question

Codes used to print in vb

reply

Great work - nice tutorial

I am new to VB. I found all the things from this one page what I needed. Great stuff. Keep it up !!!!!!!!!

reply

KEep it up guyz!

Your site certainly helps a lot. tnx.

reply

Awesome!!

Fabuluos piece of explanation with code samples. Some thing i would love to bookmark.

reply



Sat, 12/26/2009 - 18:05 — Anonymous (not verified)

Tue, 09/01/2009 - 23:27 — lrio

Fri, 04/24/2009 - 03:15 — Dan.tindi (not verified)

Thu, 03/05/2009 - 06:49 — ramdas

Thu, 02/12/2009 - 10:09 — marksman78

Fri, 07/10/2009 - 11:10 — Juned (not verified)

Nice

Great tutorial, and nice code...Everything needed to explain to someone just starting while also informational to

someone not yet used to DAO syntax...

Thanks, and keep up the good work. :)

reply

Pls. help me with this problem

I would like to know if how can I store the data inputted by the user from the textboxes to the recordset?...

also, I would like to know if what is the code to display the data onto the listview or in a form of a table?

reply

Great work

This is a great refferencing material. Honestly A-Z of what i needed. keep up. and up-to-date.

reply

One of the Most organized

One of the Most organized and informative sites i've ever seen.......thanks a lot for everything.....

reply

pls help me with this problem

private sub cmddiv_click()

txtresult.text=val(txtn1.text) / val(txtn2.text)

End sub

What I really want this code to do is to divide numbers lets say 72 divide by 27 which will give 2.6666667 but what I

want is that the result should be 2.67 that is there should be only two diugits after the decimal and last number

should be approximated.

thanks

reply

Reply

You need to change ur code a li'lbit as follows:-



Sat, 04/04/2009 - 05:39 — Tim (not verified)

Sat, 02/21/2009 - 23:35 — eian (not verified)

Private Sub cmddiv_click()

txtresult.Text = Round(Val(txtn1.Text) / Val(txtn2.Text), 2)

End Sub

Happy to help u!

reply

Format

try this

txtresult.text= format(val(txtn1.text) / val(txtn2.text)), "####.##")

reply

re

Dim ans as double

ans = val(txtn1)/val(txtn2)

txtresult = ans

reply

Post new comment

Your name:

Anonymous

E-mail:

The content of this field is kept private and will not be shown publicly.

Homepage:

Subject:

Comment: *



Unless otherwise noted, all content on this site and in the source samples is Copyrighted © 2011 by the owner of

vb6.us. All rights reserved - Contact Information

Allowed HTML tags: <a> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd>

Lines and paragraphs break automatically.

More information about formatting options

Preview



Using DAO (Data Access Objects) Code _ Visual Basic 6 (VB6

Documents

Transcript of Using DAO (Data Access Objects) Code _ Visual Basic 6 (VB6