General CASE Function (searched_case_function)

				
<searched_case_function>::=
  CASE 
    WHEN <search_condition> THEN <result_expression> 
    [...]
    [ELSE <default_expression>]
  END

<result_expression>::=
  <expression>

<default_expression>::=
  <expression>
				
			

Examples

SQL Tutorial, Functions

Explanation

CASE checks the search conditions ( search_condition) in succession. As soon as a search condition that is true is found, the result of the general CASE function is the value of the expression result_expression that belongs to the search condition.

If no true search expression is found, then CASE gets the result of the expression default_expression. If  default_expression is not specified, the result of CASE is the NULL value.

All search conditions without ROWNO Predicate are permissible. The data types of the expressions result_expression and default_expression must be comparable.