Sams Teach Yourself SQL in 21 Days, Fourth Edition

Placing Conditions on Queries

If you ever want to find a particular item or group of items in your database, you need one or more conditions. Conditions are contained in the WHERE clause. In the preceding example, the condition is

NAME = 'BROWN'

To find everyone in your organization who worked more than 100 hours last month, your condition would be

NUMBEROFHOURS > 100

Conditions enable you to make selective queries. In their most common form, conditions comprise a variable, a constant, and a comparison operator. In the first example, the variable is NAME, the constant is 'BROWN', and the comparison operator is =. In the second example, the variable is NUMBEROFHOURS, the constant is 100, and the comparison operator is >. You need to know about ...