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

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

by John L. Viescas, Michael J. Hernandez
September 2007
Intermediate to advanced content levelIntermediate to advanced
672 pages
13h 23m
English
Addison-Wesley Professional
Content preview from SQL Queries for Mere Mortals: A Hands-On Guide to Data Manipulation in SQL, Second Edition

Subqueries as Column Expressions

In Chapter 5, Getting More Than Simple Columns, you learned a lot about using expressions to generate calculated columns to be output by your query. We didn’t tell you then that you can also use a special type of SELECT statement—a subquery—to fetch data from another table, even if the table isn’t in your FROM clause.

Syntax

Let’s go back to the basics and take a look at a simple form of a SELECT statement in Figure 11-1.

Figure 11-1. The syntax diagram for a simple SELECT statement

This looks simple, but it really isn’t! In fact, the value expression part can be quite complex. Figure ...

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Publisher Resources

ISBN: 9780321444431Purchase book