MySQL CASE Function
Go through conditions and return a value when the first condition is met:
WHEN Quantity > 30 THEN "The quantity is greater than 30"
WHEN Quantity = 30 THEN "The quantity is 30"
ELSE "The quantity is under 30"
Definition and Usage
The CASE statement goes through conditions and return a value when the first condition is met (like an IF-THEN-ELSE statement). So, once a condition is true, it will stop reading and return the result.
If no conditions are true, it will return the value in the ELSE clause.
If there is no ELSE part and no conditions are true, it returns NULL.
WHEN condition1 THEN result1
WHEN condition2 THEN result2
WHEN conditionN THEN resultN
|condition1, condition2, ...conditionN||Required. The conditions. These are evaluated in the same order as they are listed|
|result1, result2, ...resultN||Required. The value to return once a condition is true|
|Works in:||From MySQL 4.0|
The following SQL will order the customers by City. However, if City is NULL, then order by Country:
WHEN City IS NULL THEN Country