build a database iv: create queries for a new access database overview: ask your data — create...
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Build a database IV: Create queries for a new Access database
Overview: Ask your data — create queries
It’s time to create queries, one of the most powerful tools in your database.
Say you want to know how many computers you own. You can build a query to fetch that data and total the numbers. Queries can also provide data for your forms and reports, which can help make your database easier to build and use.
This course introduces queries and explains how to create the most common type, a select query.
Build a database IV: Create queries for a new Access database
Course goals
• Use the Query Designer to create a select query that returns data from a single table.
• Create a select query that asks you to enter parameters, then returns results that match those parameters.
• Use a formula in a query to calculate a sum.
• Use the Query Wizard to create a select query that returns data from two tables.
• Use a text expression to concatenate fields.
Build a database IV: Create queries for a new Access database
Get answers from your data
Your new asset-tracking database is coming along.
You have tables, relationships, and data, so the next step is to build some queries.
Specifically, you’ll create select queries. They’re components that retrieve and process your data and display the results in a datasheet.
The query in the picture takes asset data from the first table, the names of technicians from the second table, and displays the result in a way that you can consume.
Build a database IV: Create queries for a new Access database
The basics of creating select queries
Access provides two primary ways to create select queries — the Query Wizard and the Query Designer. Regardless of the tool you use, you follow some common steps to create the query.
1 Start by choosing a recordsource for the query. A recordsource can be one or more tables, one or more queries, or a combination of the two.
From the recordsource, select the fields that you want to see in the query.
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Build a database IV: Create queries for a new Access database
The basics of creating select queries
Access provides two primary ways to create select queries — the Query Wizard and the Query Designer. Regardless of the tool you use, you follow some common steps to create the query.
3 Add any sorting, filtering, or other selection criteria to your queries. For example, if you use the criteria shown in the picture, the query will only return data for assets purchased after May First of 2010.
4 After you finish adding fields and any selection criteria, run your query to see if it gives you the correct results.
Build a database IV: Create queries for a new Access database
Ways to use query results
When you run a select query, Access displays the results in a datasheet.
The result is called a recordset, and you can work with it in the same way that you work with a datasheet.
For example, you can add or change data, and Access will write your changes to the tables that serve as the recordsources for your query.
Build a database IV: Create queries for a new Access database
Ways to use query results
You can also use your recordsets to provide data for forms, reports, and even other queries.
For example, if you want a report on the computers that you need to replace, you can create a query that returns that data, and then quickly build your report.
The picture shows this. The query returns only those records where an asset has been marked for retirement.
Build a database IV: Create queries for a new Access database
Query a single recordsource
The Query Designer gives you the most control over a select query.
It also makes it easy to create a query that uses a single table as a recordsource.
Build a database IV: Create queries for a new Access database
Query a single recordsource
For example, this type of query makes it easy to list your assets and their purchase dates, as shown here.
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On the Create tab, in the Other group, click Query Design. The designer starts and displays the Show Table dialog box.
In the dialog box, select your recordsource. You can use a combination of tables and queries, and the ones you select appear in the upper section of the designer.
Build a database IV: Create queries for a new Access database
Query a single recordsource
For example, this type of query makes it easy to list your assets and their purchase dates, as shown here.
3 In your recordsource, double-click the fields that you want to see in your recordset, or results. Your choices appear in the bottom section of the designer.
4 When you finish adding fields, go to the Design tab on the Ribbon, and in the Results group, click Run. Your record then appears as a datasheet.
Build a database IV: Create queries for a new Access database
Make a query ask you for input
The type of query that you created in the previous section can return a lot of data. A common way to limit what the query returns is to use a parameter.
Put simply, parameters make the query ask for input before it runs.
So if, say, you only want to see records between certain dates, you can add parameters that make the query ask you for starting and ending dates. The query will give you just the records that fall between those dates.
Build a database IV: Create queries for a new Access database
Make a query ask you for input
In other words, parameters are a type of filter that you build in to your query.
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Open the query in Design view, and in the Criteria row of the field you want to filter, enter your parameter.
When you run the query, that criteria asks you for a start date, then an end date, and it returns only the records that fall within the dates you specify.
Build a database IV: Create queries for a new Access database
Use a formula in a query
Another common way to alter the selection criteria in a query is to add a function.
For example, if you want to know how much your company spent on office furniture last year, you can add an aggregate function to the query and the sum will appear in your results.
Build a database IV: Create queries for a new Access database
Use a formula in a query
The picture shows the process.
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Open your query in Design view.
On the Design tab, in the Show/Hide group, click Totals. The Total row appears in the designer.
In the field where you want to use the function, click the Total row and select a function from the list.
Build a database IV: Create queries for a new Access database
Use a formula in a query
The picture shows the process.
When you run your query, the results include your calculation.
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Build a database IV: Create queries for a new Access database
Query multiple recordsources
Finally, you can use multiple tables, or other queries, as the recordsource for a new query.
The Query Wizard is the easiest way to do that type of job, especially if you’re new to Access.
This type of query is a way to answer questions such as which assets came from which suppliers.
Build a database IV: Create queries for a new Access database
Query multiple recordsources
The picture shows the process.
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On the Create tab, in the Other group, click Query Wizard.
Complete the wizard. As part of that process, select the tables and fields you want to use as your recordsource, and ...
Build a database IV: Create queries for a new Access database
Query multiple recordsources
The picture shows the process.
3 Give your new query a descriptive name. Remember to avoid using spaces in the name.