Pasewark & Pasewark 1 Access Lesson 3 Creating Queries Microsoft Office 2007: Introductory

1 Pasewark & Pasewark

Access Lesson 3Creating Queries

Microsoft Office 2007: Introductory

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Objectives

Create a query using a Wizard. Sort and filter data in a datasheet. Create a query in Design view. Create relationships in a database. Create a table based on more than one

table. Use operators in a condition in a query. Calculate data using a query.

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Vocabulary

And operator Ascending AutoFilter Calculated field Common field Condition Criteria Criterion Descending

Detail query Exact match condition Expression Filter Filter By Form Filter By Selection Foreign key Join line Matching field

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Vocabulary (continued)

Multitable query One-to-many relationship Or operator Primary table Query Range-of-values condition Referential integrity

Related table Relationship Run Simple Query Wizard Sort Subdatasheet Summary query Total row

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Creating a Query with the Simple Query Wizard

A query is a database object that lets you ask the database about the data it contains. The result of a query is a datasheet that includes the records you asked to see.

A condition (also called a criterion) is a way of telling the query which data you are interested in seeing.

When the condition has two or more parts, such as customers who have ordered a specific part and live in a certain zip code, the two conditions are called criteria.

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Creating a Query with the Simple Query Wizard (continued)

A query is based on a table, and some queries are based on more than one table. When you open a query object, you run the query.

An easy way to create a query is to use the Simple Query Wizard, which asks you what data you want to see by letting you select options in dialog boxes.

A detail query shows every field in each record. A summary query lets you summarize relevant data, such as adding the field values in a column that stores price data.

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Sorting Data

When you view a table or query datasheet, the records might not appear in the order that you need.

When you view field values in ascending or descending order from A to Z or from smallest to largest, you apply a sort to the field.

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Filtering Data

A filter temporarily displays records in a datasheet based on the condition that you specify.

When you use Filter By Selection, you select a field value (or part of a field value) in a datasheet, and then click the Selection button in the Sort & Filter group on the Home tab.

You can use Filter By Form when you need to display records that contain one or more values based on the values stored in one or more fields.

An easy way to sort and filter data using these same options is to use an AutoFilter. An AutoFilter is a menu that opens when you click the arrow on the right side of a field selector.

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Creating a Query in Design View

For a table datasheet, using a sort or a filter is your only method to change the way data is displayed in a table or query datasheet.

For a query datasheet, however, you have more sorting and filtering options if you create a query in Design view. In the Query Design window, you build and change the query using the query design grid.

Moving and Sorting Fields in Design View: You can select a sort order for a field by setting the sort order in the field’s Sort box in the design grid.

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Creating a Query in Design View (continued)

Adding a Condition to a Field: If the question is “Which orders contain an order for Product ID 1701?” then you need to add a condition to the query design before you run it. To add a condition to a field, click in the field’s Criteria box, and then type the condition.

Running a Query: You can run the query by clicking the Run button in the Results group on the Query Tools Design tab. When you run a query, the results appear in a query datasheet.

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Creating Table Relationships

When a database contains more than one table, the feature of the database management system that lets you connect the data in the tables is a relationship.

To create a relationship between two tables, you must design the tables so they contain a matching field.

A matching field is a field that appears in both tables, has the same data type, and contains the same values. A matching field is also called a common field because it is common in both tables involved in the relationship.

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Creating Table Relationships (continued)

You can create different types of relationships depending on the data used in the tables you are relating.

The most common relationship is a one-to-many relationship. Other types include one-to-one and many-to-many.

In a one-to-many relationship, one record in the first table (called the primary table) can match many (actually, zero, one or many) records in the second table (called the related table).

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The common field in the related table is called a foreign key when it is used in a relationship. In the primary table, the common field is usually the table’s primary key.

When you relate tables, Access uses a set of rules to ensure that there are matching values in the common field used to form the relationship, both at the time you create the relationship and as you enter data in the tables after you create the relationship. This set of rules is called referential integrity.

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Referential integrity protects the data in the tables to make sure that data is not accidentally deleted or changed, resulting in inconsistent data.

Viewing Related Records: After creating a one-to-many relationship between two tables, you can view the data in the related table by opening the datasheet for the primary table. Clicking the expand indicator opens a subdatasheet, which contains the related records in the related table. You can use the subdatasheet to make changes to the related records.

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Creating a Multitable Query

Queries that are based on more than one table are sometimes called multitable queries.

After you add two related tables to the query design, a join line shows the relationship between the tables.

The join line connects the common field used to relate the tables. It also defines the type of relationship by using the “1” to represent the “one” side of the relationship and the infinity symbol to represent the “many” side of the relationship.

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Using Operators in a Condition

If a query selects records for products that are out of stock, this is called an exact match condition because the records must contain the value 0 in the Units In Stock field to be displayed in the query datasheet.

Another type of condition causes a record to be displayed in the query datasheet when the record matches a range of values. This is called a range-of-values condition.

The And operator selects records that match all of two or more conditions in a query

The Or operator selects records that match at least one of two or more conditions in a query.

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Calculating Data

You can use a query to perform calculations on the data selected by a query. Access provides two ways to calculate data in a query: using the Total row and creating a calculated field.

Total Row: You can use the Total row to get a quick count of the number of values in a column. When the field contains numeric data, such as numbers or currency values, the Total row also includes functions that calculate the total of the values in a column or the average, minimum, or maximum value in a column.

Calculated Field: When a field displays a value that is calculated using other fields in the query, it is called a calculated field. The calculation itself, such as [Current Date] – [Birth Date], is called an expression.

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Summary

A query is a database object that lets you ask the database about the data it contains. You can create a query quickly using the Simple Query Wizard.

Change the way data is sorted in a datasheet by applying an ascending or a descending sort order to one of the fields.

Use a filter in a datasheet to temporarily display records in a datasheet based on a condition that you specify. Filter By Selection lets you select a field value in a datasheet and then filter out records that do not match the filter. Filter By Form lets you display records that match a value you select in a field.

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Summary (continued)

An AutoFilter opens when you click the arrow on a field selector.

You can use an AutoFilter to sort and filter data. You can also move and sort fields in Design view. To run a query, click the Run button in the Results group on the Query Tools Design tab.

When you need to create a query that uses conditions to select records, create the query in Query Design view.

Use the Relationships window to create relationships between tables in a database by joining tables with a field that contains matching field values.

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Summary (continued)

A one-to-many relationship exists when one record in the primary table matches zero, one, or many records in the related table. Referential integrity is the set of rules that Access uses to protect data in the tables and to make sure that data is not accidentally deleted or changed.

A multitable query is a query that is based on two or more tables.

When you need to use a query to search for records that match a range of values, use a relational operator in the query design.

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Summary (continued)

When you need to select records that match all of two or more conditions in a query, use the And operator by placing the criteria in the same Criteria row in the design grid.

When you need to select records that match at least one of two or more conditions in a query, use the Or operator by placing the criteria in different Criteria rows in the design grid.

In Access, you can perform calculations by using the Total row in a datasheet or by creating a calculated field in the design grid.

Documents

Pasewark & Pasewark 1 Access Lesson 3 Creating Queries Microsoft Office 2007: Introductory