Post on 04-Apr-2018
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access session 4
Using Queries to Select Data
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Database Operation in Table Datasheet view Retrieve, sort and group data
Limit results
Evaluate expressions
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Table Datasheet view Operations(Sort and Filter)
how to. Records menu
Table Datasheet toolbar
Filter by Selection Excel concept ofAutoFilter
Filter by Form Excel concept of Custom
Filter
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Comparison and Logical Operators
Comparison Logical= Equals
OrMeets any onecondition> Greater than
>= Greater than or equal And Meets allconditions< Less Than
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Query Preliminaries
Queries are used to sort, filter, add, delete,and modify data in MS Access databases
use queries to request data for forms,
reports, and controls when an object relieson specific data rather than on all the datain the underlying table.
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Query Types 1/2
Select: retrieve data that meets specificconditions, group records for viewingsummary data, and display calculations
performed on data fieldsAction: modify existing data in some way,
used to delete, update, and append data orto create a new table.
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Query Types 2/2
Parameter: prompt you for criteria beforerunning the actual query
Crosstab: summarize data and then groupthe summarized values into categories
SQL: include union, pass-through and data-definition queries, require specific SQLcommands, that you must compose in SQL
view
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the query environment
query Design view: identify the tables and queriesthat you want to include in your query. and create& view queries
field list: upper part window displays a field list for each
table or query design grid: lower part window, define the querys fields
and accept expressions as criteria for limiting the resultsof the query
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SQL view: translated query design view intoJet Structured Query Language.
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Common SQL keywords
AS: creates a clause that specifies an expressionor value and the field name associated with it
DISTINCTROW: exclude duplicate records from
the query FROM: Create a clause specifying the table or
query from which fields are taken for the query
ORDER BY: Crates a clause containing a list offields to be included in the query
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SELECT: creates a clause containing a listof fields to be includes in the query
UNION: Combines two sets of records into
a single set WHERE: Creates a clause with a condition
(or set of conditions) for filtering query
records.
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The Simple Query wizard Summarizing Data using the Wizard
Retrieving Data using the Design view
1. click new, then add fields from the Show tablewindow
2. execute the query using the Run button from
the Query Design toolbar
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5 methods for adding fields to thedesign grid
double-click the field in the field list drag the field to a column
double-click or drag the * in the field list
field drop-down list
type the field name in a columns Field cell
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other design grid components
Sorting Records: using the Sort cell Computing totals for group records: using
Group by Drop-down list (view menu,
totals) Limiting Data: using the Criteria or Or cell
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Crosstab
Crosstab query is a query that groupssummarized data by categories, a morecompact way to group and summaries record
Crosstab vs PivotTable both summarize data using aggregate functions
PivotTables are more powerful because they candisplay the detailed data behind those subtotals and
grand totals without affecting the groups
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Crosstab vs PivotTable (cont.) column headings: PivotTables (multiple) while
Crosstab (one)
PivotTables also include crossfoot totals,Crosstab none
PivotTables: quicker to produce and moreflexible that crosstab queries
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To sum it up
datasheet sorting & filtering vs. queries Both can be manipulated using the design grid
area
Queries: saved objects Manipulate the query design view, design
grid area