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Chapter 11. Advanced Query Techniques > Using SQL to Update Data - Pg. 455

Advanced Query Techniques 455 Figure 11.37. A solution to eliminate propagation of Null s. This expression uses the Nz function to convert the Null values to 0 before the two field values are added together. Subqueries Subqueries allow you to embed one SELECT statement within another. By placing a subquery in a query's criteria, you can base one query on the result of another. Figure 11.38 shows an example. The query pictured finds all the clients without projects. The SQL statement looks like this: