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Q. 1 what is Net? Explain its features.

Answer-NET is the framework for which we develop applications. It sits in between

ourapplicationprograms and operating system. Applications developed for NET run

inside NET and are controlled by NET. It supports both Windows and web

applications. NET provides an object oriented environment. It ensures safe execution ofthe code by performing required runtime validations. For example, it is never possible to

access an element of an array outside the boundary. Similarly, it is not possible to a

program to write into another programs area, etc. The runtime validations performed

by .NET makes the entire environment robust.

Components of NET: -NET framework has two main components. They are:

1. Common Language Runtime

2. NET class library

Features of NET: - The following are major features of NET. We will use

these features throughout journey. Here is just a brief introduction to all key features of

NET.

Assemblies: - An assembly is either a DLL or EXE that forms a part of anapplication. It

contains MSIL code that is executed by CLR. The following are other important points

related to an assembly:

The four parts of an assembly are: -

Assembly Manifest - Contains name, version, culture, and information about referenced

assemblies.

Type metadata - Contains information about types defined in the assembly.

MSIL MSIL code.

Resources - Files such as BMP or JPG file or any other files required by application.

Common Type System:- Common Type System (CTS) specifies the rules related

to datatypes that languages must follow. As programs written in all languages are

ultimately converted to MSIL, data types in all languages must be convertible to certain

standard data types.

Cross-language Interoperability: - NET provides support for language interoperability.

However, it doesnt mean every program written in a language can be used by another

language. To enable a program to be used with other languages, it must be created by

following a set of rules called Cross Language Specifications (CLS).

Q. 2 Explain method to create a new windows user interface.
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Answer-Create a Windows Forms Application: -

Close the project from Lesson 1, if it is still open in Visual Basic Express, and then on

the File menu, click New and then selectNew Project.

This will open up a new dialog called New Project in which you have the option to select

the template that will be used to create the plug-in application.

As you are working with Visual Basic Express, your installed templates are under the

Visual Basic category. In the centre of the dialog, you can see various application

templates that are available to you, the choice of which depends on the type of

application you wish to create. As youre creating a simple, standalone EXE with a

dialog-based user interface, select the Windows Forms Application template. You now

need to select a name for your project. Enter My First Invent or Plug-in in the box near

the bottom of the New Project dialog and select OK: The basic solution containing your

project should now be created and loaded into the Visual Basic Express editor.

Q. 3 What is CLR?

Answer-The Common Language Runtime (CLR) is the environment where all programs

in NET are run. It provides various services, like memory management and thread

management. Programs that run in the CLR need not manage memory, as it is completely

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taken care of by the CLR. For example, when a program needs a block of memory, CLR

provides the block and releases the block when program is done with the block. All

programs targeted to .NET are converted to MSIL (Microsoft Intermediate Language).

MSIL is the output of language compilers in NET . MSIL is then converted to native

code by JIT (Just-in Time Compiler) of the CLR and then native code is run by CLR. As

every program is ultimately converted to MSIL in .NET, the choice of language is pure

personal. A program written inVB.NET and a program written in C# are both converted

to MSIL. Then MSIL is converted to native code and run. So, whether you write

program in C# or VB.NET at the end it is MSIL all that you get. It is believed VB6.0

programmers will migrate to VB.NET and C++ and Java programmers switching

to .NET will prefer to use C# as it more resembles those languages.

For Java programmers, MSIL in .NET is same as Bytecode in concept. CLR is

same as JVM (Java virtual machine). So the inevitable question is Is .NETplatform

independent like Java? The answer is technically YES. A program written for .NET can

run on any platform as long as .NET is made available on that platform. As ofnow, .NET runs only on Windows. So, .NET is technically platform independent but not

real, at least not now. Efforts are on to make .NET run on Linux. The project is called as

Mono and is currently being developed. Though some people doubt the seriousness of

Microsoft, I will not be surprised if Microsoft comes out with NET on Linux in future. If

that happens, all your VB NET, and C# programs can run as they are on both Windows

and Linux.

Q. 4 What do you understand by class view window? Explain the utility of

immediate window.

Answer-You can use the Class View window to view the class structure of your C++program. Classes are displayed in an outline format that allows you to navigate through

the hierarchy to display the member functions for each class. A special branch of the

hierarchy called Globaldisplays global functions.

You can also use the Class View window to view function code and set

breakpoints for a class.

Displaying the Class View window

Follow these steps to open the Class View window:

Select View Classes from the C++ menu, or click on the View Classes button in

the toolbar. A Class View window is displayed that shows the class hierarchy of your C+

+ program. Figure-1 shows an example of the Class View window.
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Figure-1 the Class View window

Viewing code from the Class View window

Follow these steps to view the source code for a class:

Display the Class View window.

Click the right mouse button on a member function. A Class View window menu is

displayed Figure-2

Figure -2 The Class View window menu

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Select View Source from the Class View window menu to display the source code for the

function.

Note

You can also double click the left mouse button on a member function to display the

function source.

Select Set or Edit Breakpoint... from the Execute menu if you want to add a breakpoint

within the code you are viewing. Refer to the next section for information on how to set a

breakpoint at function entry.

The Immediate Window is your most valuable ally while debugging code. The

Immediate Window is the equivalent of a debug window that allows you to watch the

values of the variables in your code. (Bring up the Immediate Window by clicking on the

View/Immediate Window Menu Option for Access v 2.0; View/Debug Window Menu

Option for Access v 8.0)

Immediate Window

The Immediate Window can be used to return values, set values and test the validity of

conditions.

1. Putting a question mark before a variable or condition (e.g. ?MyVar) returns the value

of MyVar. But remember that MyVar must be a variable local to the procedure you are

stepping through or it must be a global variable. Asking for the value of a variable that is

not declared in the current procedure will give you an error.

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2. To set the value of MyVar while stepping through your code, you can bring up the

Immediate Window and set the value just like you would in the Access Basic code.

MyVar = "The new value of this variable"

3. You may terminate a program by typing

End

in the Immediate Window.

4. If you are a teeny bit lazy about typing in the variable names in the Immediate

Window each time you want to check their values, you could use this alternative instead:

Debug.Print MyVar

If you put this line at strategic points in your code you can see your code run through

uninterrupted andsee the values in the Immediate Window!! Since there is always a

downside to everything, there is one here too. This slows down the execution speed ofyour code tremendously. So if you do choose to use this then you either comment out

these lines or delete them entirely from your modules.

5. (Access v 2.0 only) One trick is to ensure that there are at least two line breaks

between each variable whose value you wish to check. You may have noticed that if you

write in two consecutive lines like:

?MyVar

?MyOtherVar

and if you put the cursor on the first line and hit to check the value of MyVaragain, then the second line is overwritten by the value of MyVar, even if it is empty. So,

if you skip a line, you can keep using these two lines over and over again without having

to retype them in every time you want to check the values.

(This does not happen in Access v 8.0)

We use the Immediate Window extensively while testing our code. To check values, to

run functions. YES! You can execute functions or subroutines by ....

?MyFunction(Arg1, Arg2)

or

?MySub Arg1, Arg2

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Q. 5 Explain subroutine and control statement in VB.NET.

Answer-Subroutine:-Subroutines can be thought of as miniature programs. A subroutine

has a name attributed with it, much like a variable does. Unlike a variable, a subroutine

doesn't hold data. Instead, it holds code. When the code in a subroutine is executed, the

subroutine is said to be "called". Therefore, one subroutine can "call" another subroutine.Some subroutines are called automatically when certain actions are performed. For

example, the Form_Load subroutine is automatically called when a form loads. This is

where you have been inserting your test code before. What you were actually doing was

adding code to this subroutine.

The declaration of a subroutine has an optional keyword that can be used before "Sub".

You may enter a keyword representing scope here. "Private" and "Public" are examples

of scopes. You may have noticed that the Form_Load subroutine has the word "Private"

before "Sub". This declares that this subroutine has a Private scope. If you don't specify

the scope of a subroutine, Visual Basic will use a default scope. You should never rely ondefault scope, however. Get in the habit of always explicitly declaring the scope of your

subroutines.

Control statement:-

Control Statements are used to control the flow of program's execution. Visual Basic

supports control structures such as if... Then, if...Then ...Else, Select...Case, and Loop

structures such as Do While...Loop, While...Wend, For...Next etc method. Then selection

structure performs an indicated action only when the condition is true; otherwise the

action is skipped.

Syntax of the If...Then selection

If Then

statement

End If

e.g.: If average>75 Then

txtGrade.Text = "A"

End If

If...Then...Else selection structure

The If...Then...Else selection structure allows the programmer to specify that a different

action is to be performed when the condition is True than when the condition is False.

Syntax of the If...Then...Else selection

If Then

statements

Else

statements

End If

e.g.: If average>50 ThentxtGrade.Text = "Pass"

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Else

txtGrade.Text = "Fail"

End If

Nested If...Then...Else selection structure

Nested If...Then...Else selection structures test for multiple cases by

placing If...Then...Else selection structures inside If...Then...Else structures.

Syntax of the Nested If...Then...Else selection structure

You can use Nested If either of the methods as shown above

Method 1

If < condition 1 > Then

statements

ElseIf < condition 2 > Then

statements

ElseIf < condition 3 > Then

statements

Else

Statements

End If

Q. 7 Explain following properties of VB.NET:

Answer-(i)Anchoring-Start a new windows projects. Add two textboxes to your form,

and set the MultiLine properties of both to True. Change the height of the boxes.

Click on Textbox1 and locate the Anchor property in the Properties box:

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The default is to anchor the control to the Top, Left edge of the form. Click the arrow to

reveal a curious drop down box:

The button in the middle represents your control. The big white areas are rather

confusing - they don't actually do anything! To change the property, you click the smaller

grey or white rectangles between the big white rectangle. Click again to deselect it. In the

image below, the property has been changed so that the textbox is anchored to the Top,

Left and Right sides of the form:

The next image has the textbox anchored to the Right and Bottom edges of the Form:

Notice where the cursor is in the images, and what has been changed. Click the arrow on

the drop down box to confirm your choices.

To see what effect this all has, do the following:

Set the Anchor property of Textbox1 on the default ofTop, Left

Change the Anchor property of Textbox2 to None (all the small rectangles should

be white.)

Run your programme and drag the edges of the Form outward. This will resize

your form

What you should notice is that Textbox1 stays where it is, and that the left edge of

Textbox2 moves.

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Stop your programme from running. Change the Anchor properties of the two textboxes

to anything you like. Run your form again and watch what happens. Try anchoring one

textbox to the left and right of the form. Watch what happens.

But anchoring a control to an edge of the form is a useful property to get used to, if you

have a form that can be resized and want your controls to stay where they are.

(ii)Docking

Docking is similar to Anchoring, but this time the control fills a certain area of the form.

To see how it works, click on one of your textboxes and locate the Dock property. Click

the arrow to reveal a drop down box:

This time, all the rectangles are like buttons. You can only dock to one side at a time, and

the default is None. Click a button to see what it does to your textbox. Click the middle

one, and the textbox will Fill the whole form.

Docking is quite useful when used with the splitter control and panels, allowing you to

create a Windows-style interface.

(ii) Dock (iii) Causes Validation (iv) GetChildAtpoint

Q. 10 Explain following:-

(i) OleDbCommand class:-

Command objects represent SQL commands or SQL stored procedures that you execute

in a database. For example, to retrieve data from a database, you can create a connection

object, open the connection with its Open method, and then assign the open connection

object to the Connection property of a command object. You can then assign the

command object to a command property of a data adapter, such as

the SelectCommand property (which lets you retrieve rows of data from the database

when you call the data adapter's Fill method). Besides the SelectCommand property, data

adapters also support UpdateCommand, InsertCommand,

and DeleteCommand properties, each of which takes connection objects that perform

these various functions.

As you can guess, you use OleDbCommand objects with OLE DB connections,

and SqlCommand objects with SQL Server connections. How do you place the SQL you

want to use in a command object? You can either assign that text to the command

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object's CommandTextproperty, or you can pass it to the command object's constructor,

like this, where I'm selecting all the records in the pubs database's authors table:

Dim Command1 As OleDbCommand = _

New OleDbCommand("SELECT * FROM authors")

Now I can set the type of the command, which, for SQL statements,

is CommandType.Text (this is the default), and assign an open connection to the

command's Connection property:

Dim Command1 As OleDbCommand = _

New OleDbCommand("SELECT * FROM authors")

Command1.CommandType = CommandType.Text

Connection1.Open()

Command1.Connection = Connection1

Now this command object is ready to go. In this case, I can assign it to a data

adapter's SelectCommand property and execute its SQL with the data

adapter's Fill method.

You also can use the command object's built-in methods to execute commands in a

database, no data adapter needed:

ExecuteReader Executes SQL commands that return rows. Note that this

method does notreturn a dataset, it creates a data reader, which is much more

simplistic. See "Using a Data Reader" in the Immediate Solutions.

ExecuteNonQuery Executes commands that do not return data rows (such

as SQL INSERT, DELETE, UPDATE, and SET statements).

ExecuteScalar Calculates and returns a single value, such as a sum, from a

database.

(ii) SqlCommand class:-

The SqlCommand Class is used for T-SQL, SQL statements and stored procedures to

execute against a SQL Server database. This class cannot be inherited because it is a

sealed class. The SqlCommand is a sealed class that inherits DbCommand Class and the

ICloneable interface.

public sealed class SqlCommand : DbCommand, Cloneable

The DbCommand class is a base class for database-specific classes that represent

commands. The ICloneable interface creates a new instance of a class with the same

value as an existing instance.

Sealed classes are primarily used to prevent derivation. Because they can never be used

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as a base class, some run-time optimizations can make calling sealed class members

slightly faster.

The System.Data.SqlClient namespace is used for the SqlCommand class.This

namespace is .NET Framework Data Provider for SQL Server.

SqlCommand Class Constructor

A Constructor is a method that is used for instantiating a class. It never returns a value.

Its name is the same as the class name but it might not have a parameter or it might have

parameters. The SqlCommand Class contains four types of constructors.

A. SqlCommand( )

B. SqlCommand(string)

C. SqlCommand(string,SqlConnection)

D. SqlCommand(string,SqlConnection,SqlTransaction)

To explain all of them first we need to create a table tbl_employee.

Fig 1. tbl_employee Definition

This tbl_employee table contains some data that are used in the following methods.

Here we define the SqlCommand class Constructors one by one.

(A). SqlCommand()

It is a SqlCommand class constructor. It has no parameters, which means it is a default

constructor. We will use it to create an object of a SqlCommand class.

//create connection to Sql server database

SqlConnection con = new SqlConnection(@"Data Source=SANPEEP-

PC\SANDEEP;Initial Catalog=Employee;User ID=sa; Password=123;Pooling=False");

con.Open();

SqlCommand cmd=new SqlCommand();//use SqlCommand() constructor

cmd.CommandText="select Emp_id,Emp_name,Emp_exp,Emp_address from

tbl_employee";

cmd.Connection=con;

SqlDataAdapter dap=new SqlDataAdapter(cmd);

DataSet ds=new DataSet();

dap.Fill(ds,"EmployeeTable");

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grdemployee.DataSource=ds;//grdemployee is a GridView Id

grdemployee.DataBind();

In the above code SqlCommand cmd=new SqlCommand() is used to create an object of

the SqlCommand class. In this code CommandText is a property of the SqlCommand

class object that is used to assign a string to the SqlCommand object. Inthe CommandText property we can assign a query or stored procedure for excution

against a SQL Server database in string format. Another SqlCommand class object

property is Connection which is used to assign a SqlConnection to the SqlCommand

object. The remaining code excutes in a manner shown in Figure 2.

Fig 2. Represention of DataSet connection to SqlDataAdapter

(B). SqlCommand(string)

It is an constructor of SqlCommand class that is used to create an object of the

SqlCommand class. It has one parameter that is a string type which means we pass aparameter that has a SQL query or stored procedure in a string format. Like:




con.Open();

SqlCommand cmd = new SqlCommand("select

Emp_id,Emp_name,Emp_exp,Emp_address from tbl_employee");//use

SqlCommand(string) constructor

cmd.Connection=con;//con SqlConnection class object

SqlDataAdapter dap=new SqlDataAdapter(cmd);DataSet ds=new DataSet();

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(C). SqlCommand(string,SqlConnection)

It is an another constructor of SqlCommand class. It has two parameters. The first

parameter is a string type that is used to assign a SQL Query or Stored Procedure in

string format. The second parameter is of SqlConnection type that is used to assign a

connection for a database. It is the simplest way. We mostly use it comparision above.

Like:




con.Open();

SqlCommand cmd = new SqlCommand("selectEmp_id,Emp_name,Emp_exp,Emp_address from tbl_employee",con);//use

SqlCommand(string,SqlConnection) constructor






(D). SqlCommand(string,SqlConnection,SqlTransaction)

This is another constructor of SqlCommand Class that has three parameters. The first

parameter is a string type that is used to assign a SQL query or stored procedure in string

format. The second parameter is a SqlConnection type that is used to assign a

SqlConnection to the SqlCommand. And the last parameter is a SqlTransaction type that

is used to assign which transaction we are using for a particular SqlCommand. The

SqlTransaction instance is used to define our transaction commit and rollback in our C#

code.




con.Open();SqlTransaction mytransaction = con.BeginTransaction();//a transaction begins

SqlCommand cmd = new SqlCommand("select

Emp_id,Emp_name,Emp_exp,Emp_address from

tbl_employee",con,mytransaction);//use SqlComman

(string,SqlConnection,SqlTransaction) constructor

mytransaction.Commit();//Method of SqlTransaction






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SqlTransaction is not really used in the above metioned code; it is used when we use

more than one DML Sql Statement.

OUTPUT

The above four samples of code gives us the same output no matter which we are used.

Fig. 3 is the output of the above mentioned code.

(iii) SqlDataAdapter class

The SqlDataAdapter class is found in the System.Data.SqlClient namespace. It is a very

important class in the .NET framework. It works as a bridge between DataSet and

Database. It opens the database connection, executes the SQL statements and closes the

connection at last. There is no need to open and close the connection. It has two more

important methods Fill() and Update(). The Fill() method is used to fill the DataSet or

DataTable and Update() is used for saving the changes to the Database in same order as

the DataSet, which is made with DataSet.

Now we will work with SqlDataAdapter in our application. I have a Database student and

a Database table as "student_detail" which has one record. We take a window form

application in Visual Studio 2010 > Take 2 button and 1 DataGridView control and writethe following code.

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Data.SqlClient;

namespace adapter

{

publicpartialclassForm1 : Form

{

public Form1()

{

InitializeComponent();

}

SqlDataAdapteradapter;

DataSet ds;

DataTable dt;

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string connstring = "database=student;server=.;user=sa;password=wintellect";

privatevoid Form1_Load(object sender, EventArgs e)

{

}

privatevoid btndataset_Click(object sender, EventArgs e){

// Using DataSet

adapter = newSqlDataAdapter("select * from student_detail", connstring);

ds = newDataSet();

adapter.Fill(ds);

dGVshowrecord.DataSource = ds.Tables[0];

//********

// Same operation can be performed by below code

//********

//adapter = new SqlDataAdapter();

//SqlConnection con = new SqlConnection(connstring);

//adapter.SelectCommand = new SqlCommand("select * from student_detail",

con);

//ds = new DataSet();

//adapter.Fill(ds);

//dGVshowrecord.DataSource = ds.Tables[0];

}

privatevoid btndatatable_Click(object sender, EventArgs e)

{

// Using DataTable


dt = newDataTable();

adapter.Fill(dt);

dGVshowrecord.DataSource = dt;

//********

// Same operation can be performed by below code

//********

//adapter = new SqlDataAdapter();

//SqlConnection con = new SqlConnection(connstring);

// adapter.SelectCommand = new SqlCommand("select * from student_detail",

con);

//dt = new DataTable();

//adapter.Fill(dt);

//dGVshowrecord.DataSource = dt;

}

}

}

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Run the application.

Output

Click on both buttons to show records from "student_detail" table.

Now we insert, delete and update records using the SqlDataAdapter class. We will use

the update() method of SqlDataAdapter and also we have to use the SqlCommandBuilder

class for performing such an operation. Add 2 buttons in your application and set

their text property to "Clear" and "Update". Replace the preceding code with the

following code.

using System;

using System.Collections.Generic;

using System.ComponentModel;using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Data.SqlClient;

namespace adapter

{

publicpartialclassForm1 : Form{

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public Form1()

{

InitializeComponent();

}

SqlDataAdapteradapter;

DataSet ds; DataTable dt;

string connstring = "database=student;server=.;user=sa;password=wintellect";

privatevoid Form1_Load(object sender, EventArgs e)

{

}

privatevoid btndataset_Click(object sender, EventArgs e)

{

// Using DataSet


ds = newDataSet();adapter.Fill(ds);// fill the DataSet

dGVshowrecord.DataSource = ds.Tables[0];// Binding DataGridView with

DataSet

}

privatevoid btnupdate_Click(object sender, EventArgs e)

{

SqlCommandBuildercmb = newSqlCommandBuilder(adapter);// Creating

instance of SqlCommandBuilder

adapter.Update(ds);// updating changes

}

privatevoid btnclear_Click(object sender, EventArgs e)

{

ds.Clear();// Clear the DataSet

}

}

}

Run the application

Output

Click the "Using Dataset" button. It will show record from Database.

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Make some changes in records of DataGridView. I have made some changes by adding

some new row and updating course of first row. Click the "Update" button. It will save

the current record of DataSet into Database.

Now click the Clear button to clear the DataSet.

Now click the "Using Dataset" button. It will show the record from the Database.

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