SQL Queries for Mere Mortals: A Hands-On Guide to Data Manipulation in SQL, 4th Edition

5Getting More Than Simple Columns

“Facts are stubborn things.”

—TOBIAS SMOLLETT GIL BLAS DE SANTILLANE

Topics Covered in This Chapter

What Is an Expression?

What Type of Data Are You Trying to Express?

Changing Data Types: The CAST Function

Specifying Explicit Values

Types of Expressions

Using Expressions in a SELECT Clause

That “Nothing” Value: Null

Sample Statements

Summary

Problems for You to Solve

In Chapter 4, “Creating a Simple Query,” you learned how to use a SELECT statement to retrieve information from one or more columns in a table. This technique is useful if you’re posing only simple requests to the database for some basic facts. However, you’ll need to expand your SQL vocabulary when you begin working with complex requests. In ...