Sams Teach Yourself Transact-SQL in 21 Days, Second Edition

Summary of Search Conditions

Before we start sorting data, let's review what you've learned so far about search conditions:

• To improve overall system performance, do all your data filtering on the server. That will reduce network traffic (from transferring unnecessary rows) and simplify application programming.

• Search conditions appear in a WHERE clause. The WHERE clause must follow the table list. If no WHERE condition is specified, your query operates on the entire table.

• You can use equality, inequality, and range comparisons to test values of any data type. Range searches with datetime values should avoid using BETWEEN.

• You will need to combine search conditions with OR and AND. When you combine more than two conditions, especially when OR is ...