SQL - CASE Function
statement selects one sequence of statements to execute.
However, to select the sequence, the CASE
statement uses a selector rather than multiple Boolean expressions.
Syntax for MySQL
CASE [ selector ]
WHEN condition_1 THEN result_1
WHEN condition_n THEN result_n
Parameters or Arguments:
- 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.
If no condition is found to be true, then the CASE function will return the value in the ELSE clause, and if the ELSE clause is also omitted, then the CASE statement will return NULL.