Learn SQL Database Programming

Understanding how and when to use the WHERE clause to limit query results

The WHERE clause is placed after the FROM clause in a SELECT query. Using the example of players with more than 40 appearances in games, you can execute the following query:

USE lahmansbaseballdb;SELECT playerid, g_all, g_batting, g_defense FROM appearancesWHERE g_all > 40;

The criterion we are setting in the WHERE clause (for example, g_all > 40) is called an expression. There are different expression operators you can use.

The following are the comparison operators:

Symbol	Description	Examples
=	Equal to	column = 'text' column = 1
>=	Greater than or equal to	column >= 1
>	Greater than	column > 1
<=	Less than or equal to	column <= 1
<	Less than	column ...