Parameters or Arguments:
selector - an optional expression, whose value is used to select one of several alternatives.
condition_1, ... condition_n - Evaluated in the order listed. Once a condition is found to be true, the CASE function will return the result and not evaluate the conditions any further.
result_1, ... result_n - The value returned once a condition is found to be true.
CASE [ selector ]
WHEN condition_1 THEN result_1
WHEN condition_n THEN result_n
In this CASE function example, the expression is quantity whose value would be compared to each of the conditions until one is met.
Then the corresponding value would be returned by the CASE function.
WHEN > 10 THEN 'The quantity is greater than 10'
WHEN = 10 THEN 'The quantity is 10'
ELSE 'The quantity is something else'
In this CASE function example,
an expression has not been included so each condition is individually evaluated
and can be completely different and unique. When a condition is met, the corresponding value would be returned.
WHEN a < b THEN 1
WHEN supplier_type = 'clothing' THEN 2