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Summary
As you can see, Microsoft gives you a sophisticated query builder for constructing complex and powerful queries. Action queries let you modify table data without writing code; you can use these queries to add, edit, or delete table data. The Unique Values and Top Values properties of a query offer you flexibility in determining exactly what data is returned in your query result.You can do many things to improve your queries' efficiency. A little attention to the details covered in this chapter can give you dramatic improvements in your application's performance.Other special types of queries covered in this chapter include Crosstab queries, outer joins, and self joins. Whatever you can't do by using the graphical QBE grid, you can accomplish by typing the required SQL statement directly into the SQL View window. In this window, you can type Access SQL statements or use SQL Pass-Through to type SQL statements in the SQL dialect that's specific to your back-end database. Once you harness the power of the SQL language, you can perform powerful tasks such as modifying the record source of a form, or report at runtime.
