Introduction to SQL: Mastering the Relational Database Language, Fourth Edition/20th Anniversary Edition

Chapter 5. SELECT Statement: Common Elements

Introduction

This first chapter dealing with the SELECT statement describes a number of common elements that are important to many SQL statements and certainly crucial to the SELECT statement. For those who are familiar with programming languages and other database languages, most of these concepts will look familiar.

We cover, among others, the following common elements:

• Literal

• Expression

• Column specification

• User variable

• System variable

• Case expression

• Scalar function

• Cast expression

• NULL value

• Compound expression

• Aggregation function

• Row expression

• Table expression

Literals and Their Data Types

Literals have been used in many examples of SQL statements in the previous chapter. A literal is a fixed or unchanging ...