MySQL in a Nutshell, 2nd Edition

Name

BOOL, BOOLEAN

Synopsis

BOOL

This data column type, BOOL, is synonymous with BOOLEAN and TINYINT(1). In fact, if you set a column to this type and then use the DESCRIBE statement to see the description of the column, it will show it as a TINYINT(1). It can be useful for a simple logical column in which you want only a true or false value. For example, if a column labeled active was a BOOLEAN type, you could do something like the following:

SELECT client_name AS 'Client', 
IF(active, 'Active', 'Inactive') AS Status
FROM clients;

This statement will show each client name in the table with the words Active or Inactive next to each name. This works because the IF() function checks for a value of 1 or 0 for the value given; it returns the second parameter given if the value is 1, the third parameter if the value is 0.