3. Maintaining and Querying a Database

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Maintaining andQuerying a Database


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Objectives

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y Find, modify, and delete records in a table

y Learn how to use the Query window in Design view

y Create, run, and save queries

y Update data using a query datasheety Create a query based on multiple tables

y Sort data in a query

y Filter data in a query


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Objectives

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y Specify an exact match condition in a queryy Change the font size and alternating row color in a

datasheety Use a comparison operator in a query to match a range

of valuesy Use the And and Or logical operators in queries

y Create and format a calculated field in a query

y Perform calculations in a query using aggregate functions

and record group calculationsy Change the display of database objects in the Navigation

Pane


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Updating a Database

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y Updating, or maintaining, a database is the process of

adding, modifying, and deleting records in database tables to

keep them current and accurate


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Finding Data in a Table

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y The Find command allows you to search a table or query

datasheet, or a form, to locate a specific field value or part of

a field value


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Deleting a Record

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y With the table in Datasheet view, click the row selector for

the record you want to delete

y In the Records group on the Home tab, click the Delete

button (or right-click the row selector for the record, andthen click Delete Record on the shortcut menu)

y In the dialog box asking you to confirm the deletion, click

the Yes button


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Deleting a Record

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Introduction to Queries

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y Access provides powerful query capabilities that allowyou to do the following:y Display selected fields and records from a table

y Sort records

y Perform calculations

y Generate data for forms, reports, and other queries

y Update data in the tables in a database

y Find and display data from two or more tables

y A QueryWizard prompts you for information byasking a series of questions and then creates theappropriate query based on your answers


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Query Wizard

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y When you use query byexample(QBE), you give Access

an example of the information you are requesting

y Click the Createtab on the Ribbon

yIn the Other group on the Create tab, click the QueryDesignbutton


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Query Wizard

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Creating and Running a Query

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Updating Data Using a Query

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y You can update the data in a table using a query datasheet

y After updating the query, close the table


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Creating a Multitable Query

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y A multitable query is a query based on more than one table

y If you want to create a query that retrieves data from

multiple tables, the tables must have a common field


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Sorting Data in a Query

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y Sorting is the process of rearranging records in a specified

order or sequence

y To sort records, you must select the sort field, which is the

field used to determine the order of records in the datasheet


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Using AutoFilter to Sort Data

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y The AutoFilterfeature enables you to quickly sort and

display field values in various ways

y Clicking the arrow in a column heading displays the

AutoFilter menu


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Sorting a Query Datasheet

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y In the query datasheet, click the arrow on the column heading forthe field you want to sort

y In the menu that opens, click Sort A to Z for an ascending sort, orclick Sort Z to A for a descending sort

or

y In the query datasheet, select the column or adjacent columns onwhich you want to sort

y In the Sort & Filter group on the Home tab, click the Ascendingbutton or the Descending button

or

y In Design view, position the fields serving as sort fields from leftto right

y Click the right side of the Sort text box for the field you want tosort, and then click Ascending or Descending for the sort order


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Sorting a Query Datasheet

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UsingFilter By Selection

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y A filteris a set of restrictions you place on the records in anopen datasheet or form to temporarilyisolate a subset of therecords

y In the datasheet or form, select part of the field value that

will be the basis for the filter; or, if the filter will be based onthe entire field value, click anywhere within the field value

y In the Sort & Filter group on the Home tab, click theSelection button, and then click the type of filter you want to

apply


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UsingFilter By Selection

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XPDefining Record Selection Criteria

for Queries

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y To tell Access which records you want to select, you must

specify a condition as part of the query

y A comparison operatorasks Access to compare the value

in a database field to the condition value and to select all therecords for which the relationship is true


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for Queries

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Specifying an Exact Match

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y With an exact match, the value in the specified field must

match the condition exactly in order for the record to be

included in the query results


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Appearance

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y You can change the characteristics of a datasheet, including

the font type and size of text in the datasheet, to improve its

appearance or readability

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By default, the rows in a datasheet are displayed withalternating background colors of white and light gray


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XPChanging a Datasheets

Appearance

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XPUsing a Comparison Operator

to Match a Range of Values

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for Queries

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y Multiple conditions require you to use logical operators

to combine two or more conditions

y Use the And logical operator when you want a record

selected only if two or more conditions are met

y Use the Or logical operatorwhen you place conditions in

different Criteria rows


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for Queries

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Using Aggregate Functions

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y Aggregate functionsperform arithmetic operations on

selected records in a database

y If you want to quickly perform a calculation using an

aggregate function in a table or query datasheet, you can use

theTotals button on the Home tab


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Using Aggregate Functions

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3. Maintaining and Querying a Database

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