SQL Queries for Mere Mortals: A Hands-On Guide to Data Manipulation in SQL, Second Edition

11. Subqueries

“We can’t solve problems by using the same kind of thinking we used when we created them.”

—Albert Einstein

Topics Covered in This Chapter

What Is a Subquery? Subqueries as Column Expressions Subqueries as Filters Uses for Subqueries Sample Statements Summary Problems for You to Solve

In the previous three chapters, we showed you many ways to work with data from more than one table. All the techniques we’ve covered to this point have been focused on linking subsets of information—one or more columns and one or more rows from an entire table or a query embedded in the FROM clause. We’ve also explored combining sets of information using the UNION operator. In this chapter, we’ll show you effective ways to fetch a single column from ...