As with many other tasks, you can query a database either programatically or via a user interface. The 2nd query only returns records where the value in the ArtistId column equals 1. So if there are say, three albums belonging to artist 1 , then three records would be returned. SQL is a powerful language and the above statement is very simple. You can use SQL to choose which columns you want to display, you could add further criteria, and you can even query multiple tables at the same time.
If you're interested in learning more about SQL, be sure to check out the SQL tutorial after you've finished this one! Now suppose that you want to review product subtotals, but you also want to aggregate by month, so that each row shows subtotals for a product, and each column shows product subtotals for a month.
To show subtotals for a product and to show product subtotals for a month, use a crosstab query. Note: A crosstab query cannot be displayed in an Access web app. You can modify the Product Subtotals query again so that the query returns rows of product subtotals and columns of monthly subtotals. On the Design tab, in the Query Type group, click Crosstab. In the design grid, the Show row is hidden, and the Crosstab row is displayed.
In the third column of the design grid, right-click the Field row, and then click Zoom on the shortcut menu. The Zoom box opens. In the Crosstab row, select the following values from the drop-down list: Row Heading for the first column, Value for the second column, and Column Heading for the third column.
The query runs, and then displays product subtotals, aggregated by month. For more information about crosstab queries, see Make summary data easier to read by using a crosstab query. Note: A make-table query is not available in Access web apps. For example, suppose that you want to send data for Chicago orders to a Chicago business partner who uses Access to prepare reports. Instead of sending all your order data, you want to restrict the data that you send to data specific to Chicago orders.
You can build a select query that contains Chicago order data, and then use the select query to create the new table by using the following procedure:. Note: If you see a message beneath the Ribbon about enabling the database, click Enable content. If your database is already in a trusted location, you will not see the Message Bar. In the Ship City column of the design grid, clear the box in the Show row. In the Criteria row, type 'Chicago' include the single quotation marks.
Verify the query results before you use them to create the table. In the confirmation dialog box, click Yes , and see the new table displayed in the Navigation Pane. Note: If there is already a table with the same name that you specified, Access deletes that table before running the query. For more information about using make table queries, see Create a make table query. You can use an append query to retrieve data from one or more tables and add that data to another table.
Note: Append query is not available in Access web apps. For example, suppose that you created a table to share with a Chicago business associate, but you realize that the associate also works with clients in the Milwaukee area. You want to add rows that contain Milwaukee area data to the table before you share the table with your associate.
You can add Milwaukee area data to the Chicago Orders table by using the following procedure:. On the Design tab, in the Query Type group, click Append. The Append dialog box opens. In the design grid, in the Criteria row of the Ship City column, delete 'Chicago', and then type 'Milwaukee'. In this example, the Append To row values should match the Field row values, but that is not required for append queries to work.
Note: While running a query that returns a large amount of data you might get an error message indicating that you will not be able to undo the query. Try increasing the limit on the memory segment to 3MB to allow the query to go through. For more information about append queries, see Add records to a table by using an append query.
You can use an update query to change the data in your tables, and you can use an update query to enter criteria to specify which rows should be updated. An update query provides you an opportunity to review the updated data before you perform the update.
Important: An action query cannot be undone. You should consider making a backup of any tables that you will update by using an update query. An update query is not available in Access web apps. In the previous example, you appended rows to the Chicago Orders table.
To make the data more useful in reports, you can replace the product IDs with product names, use the following procedure:. On the Design tab, in the Query Type group, click Update.
In the design grid, the Sort and Show rows disappear, and the Update To row appears. You can review which values will be changed by an update query by viewing the query in Datasheet view.
The query returns a list of Product IDs that will be updated. When you open the Chicago Orders table, you will see that the numeric values in the Product ID field have been replaced by the product names from the Products table. For more information about update queries, see Create and run an update query.
You can use a delete query to delete data from your tables, and you can use a delete query to enter criteria to specify which rows should be deleted.
A delete query provides you an opportunity to review the rows that will be deleted before you perform the deletion. Note: A delete query option is not available in Access web apps. For example, say that while you were preparing to send the Chicago Orders table from the previous example, to your Chicago business associate, you notice that some of the rows contain a number of empty fields.
You decided to remove these rows before you send the table. You could just open the table and delete the rows manually, but if you have many rows to delete and you have clear criteria for which rows should be deleted, you might find it helpful to use a delete query.
You can use a query to delete rows in the Chicago Orders table that do not have a value for Order ID by using the following procedure:. On the Design tab, in the Query Type group, click Delete. In the design grid, the Sort and Show rows disappear, and the Delete row appears. For more information about delete queries, see Create and run a delete query. All rights reserved. What is a database query? Aug 31, - 9 min read. Christina Kopecky. What is Query By Example?
Learn about the basics of databases, relationship diagrams, normalization, and SQL. Languages for database querying Query language is what allows us to actually take action on databases. Keep the learning going. Use documentation to create a file that sets up a configuration and connection to Postgres. Use documentation to create a file that sets up a configuration and connection to MongoDB.
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