Chapter 10

Using SQL

Microsoft

Access 2013

• Understand the SQL language and how to use it

• Change the font or font size for SQL queries

• Create SQL queries

• Include fields in SQL queries

• Include simple and compound criteria in SQL queries

• Use computed fields and built-in functions in SQL queries

• Sort the results in SQL queries

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Objectives

• Use aggregate functions in SQL queries

• Group the results in SQL queries

• Join tables in SQL queries

• Use subqueries

• Compare SQL queries with Access-generated SQL

• Use INSERT, UPDATE, and DELETE queries to update a database

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Objectives

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Project – Using SQL

• Create a query in SQL view

• Use simple criteria in a query

• Use compound criteria in a query

• Sort results of a query

• Group results of a query

• Join tables in a query

• Use a subquery in a query

• Update data with a query

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Roadmap

• Tap or click FILE on the ribbon to open the Backstage view

• Tap or click Options to display the Access Options dialog box

• Tap or click Object Designers to display the Object Designer options

• In the Query design area, tap or click the Size box arrow, and then tap or click the desired font size

• Tap or click the OK button to close the Access Options dialog box

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Changing the Font Size

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Changing the Font Size

• Close the Navigation Pane

• Display the CREATE tab

• Tap or click the Query Design button (CREATE tab | Queries group) to create a query

• Close the Show Table dialog box without adding any tables

• Tap or click the View arrow (QUERY TOOLS DESIGN tab | Results group) to display the View menu

• Tap or click SQL View to view the query in SQL view

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Creating a New SQL Query

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Creating a New SQL Query

• The basic form of SQL expressions is quite simple: SELECT-FROM-WHERE

• The command begins with a SELECT clause, which consists of the word, SELECT, followed by a list of those fields you want to include

• Next, the command contains a FROM clause, which consists of the word, FROM, followed by a list of the table or tables involved in the query

• Finally, there is an optional WHERE clause, which consists of the word, WHERE, followed by any criteria that the data you want to retrieve must satisfy

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SQL Commands

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SQL Commands

• Tap or click the View arrow (HOME tab | Views group) to display the View menu

• Tap or click SQL View to return to SQL view

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Preparing to Enter a New SQL Query

• To include all fields, you could use the same approach as in the previous steps, that is, list each field in the table after the word, SELECT

• There is a shortcut, however. Instead of listing all the field names after SELECT, you can use the asterisk (*) symbol

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Including All Fields

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Including All Fields

• To restrict the records to be displayed, include the word WHERE followed by a criterion as part of the command

• If the field involved is a numeric field, you simply type the value

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Using a Criterion Involving

a Numeric Field

• A simple criterion has the form: field name, comparison operator, then either another field name or a value

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Simple Criteria

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Using a Comparison Operator

• If the criterion involves a text field, the value must be enclosed in single quotation marks

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Using a Criterion Involving a Text Field

• In most cases, the conditions in WHERE clauses involve exact matches

• The LIKE operator uses one or more wildcard characters to test for a pattern match

– One common wildcard in Access, the asterisk (*), represents any collection of characters

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Using a Wildcard

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Using a Wildcard

• Compound criteria are formed by connecting two or more simple criteria using AND, OR, and NOT

– When simple criteria are connected by the word AND, all the simple criteria must be true in order for the compound criterion to be true

– When simple criteria are connected by the word OR, the compound criterion will be true whenever any of the simple criteria are true

– Preceding a criterion by the word NOT reverses the truth or falsity of the original criterion

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Compound Criteria

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Using a Compound Criterion

Involving AND

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Using a Compound Criterion

Involving OR

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Using NOT in a Criterion

• Just as with queries created in Design view, you can include fields in queries that are not in the database, but that can be computed from fields that are

– Called a computed field

– Can involve addition, subtraction, multiplication, or division

• To indicate the contents of the new field (the computed field), you can name the field by following the computation with the word, AS, and then the name you want to assign the field

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Using a Computed Field

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Using a Computed Field

• To sort the output, you include an ORDER BY clause, which consists of the words ORDER BY followed by the sort key

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Sorting

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Sorting the Results on a Single Field

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Sorting the Results on Multiple Fields

• To sort in descending order, you follow the name of the sort key with the DESC operator

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Sorting the Results in Descending Order

• The DISTINCT operator eliminates duplicate values in the results of a query

• To use the operator, you follow the word DISTINCT with the field name in parentheses

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Omitting Duplicates When Sorting

• SQL has built-in functions, also called aggregate functions, to perform various calculations

– COUNT

– SUM

– AVG

– MAX

– MIN

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Using a Built-In Function

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Using a Built-In Function

• You can assign a name to the results of a function

• To do so, follow the expression for the function with the word AS and then the name to be assigned to the result

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Assigning a Name to the Results

of a Function

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Using Multiple Functions

in the Same Command

• Grouping means creating groups of records that share some common characteristic

• When you group rows, any calculations indicated in the SELECT command are performed for the entire group

– GROUP BY clause

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Using Grouping

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Using Grouping

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Using Grouping

• The HAVING clause, which consists of the word HAVING followed by a criterion, is used to restrict the groups to be included

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Restricting the Groups that Appear

• Many queries require data from more than one table

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Joining Tables

• You can restrict the records to be included in a join by creating a compound criterion

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Restricting the Records in a Join

• When tables appear in the FROM clause, you can give each table an alias, or an alternative name, that you can use in the rest of the statement

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Aliases

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Joining a Table to Itself

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Joining a Table to Itself

• A subquery is a query within another query

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Subqueries

• You can add records to a table using the SQL INSERT command

• The command consists of the words INSERT INTO followed by the name of the table into which the record is to be inserted

• Next is the word VALUE followed by the values for the fields in the record

– Values for Text fields must be enclosed within quotation marks

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Using an INSERT Command

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Using an INSERT Command

• You can update records in SQL by using the UPDATE command

• The command consists of UPDATE, followed by the name of the table in which records are to be updated

• Next, the command contains one or more SET clauses, which consist of the word SET, followed by a field to be updated, an equal sign, and the new value

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Using an UPDATE Command

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Using an UPDATE Command

• You can delete records in SQL using the DELETE command

• The command consists of DELETE FROM, followed by the name of the table from which records are to be deleted

• Finally, you include a WHERE clause to specify the criteria

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Using a DELETE Command

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Using a DELETE Command

• Understand the SQL language and how to use it

• Change the font or font size for SQL queries

• Create SQL queries

• Include fields in SQL queries

• Include simple and compound criteria in SQL queries

• Use computed fields and built-in functions in SQL queries

• Sort the results in SQL queries

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Chapter Summary

• Use aggregate functions in SQL queries

• Group the results in SQL queries

• Join tables in SQL queries

• Use subqueries

• Compare SQL queries with Access-generated SQL

• Use INSERT, UPDATE, and DELETE queries to update a database

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Chapter Summary

Chapter 10 Complete

Microsoft

Access 2013