General CASE Statement (searched_case_statement) 

The general CASE statement (searched_case_statement) is a syntax element that is used in a routine to define a database procedure (see CREATE DBPROC[EDURE] Statement), a database function (see CREATE FUNCTION Statement), or a trigger (see CREATE TRIGGER Statement).

Syntax

<searched_case_statement> ::=
  CASE
     <searched_case_when_clause>...
    [<case_else_clause>]
  END [CASE]

<searched_case_when_clause> ::=
  WHEN <search_condition> THEN <statement>;
<case_else_clause> ::= ELSE <statement>;

Explanation

A case_statement allows the conditional execution of a statement depending on search conditions or equality of operands.

For a general CASE statement searched_case_statement, the first fulfilled search condition is determined, the associated statement executed, and the CASE statement then ended.

CASE
  WHEN digit = 0 THEN toCHAR = 'zero';
  WHEN digit = 1 THEN toCHAR = 'one';
  WHEN digit = 2 THEN toCHAR = 'two';
  WHEN digit = 3 THEN toCHAR = 'three';
  WHEN digit = 4 THEN toCHAR = 'four';
  WHEN digit = 5 THEN toCHAR = 'five';
  WHEN digit = 6 THEN toCHAR = 'six';
  WHEN digit = 7 THEN toCHAR = 'seven';
  WHEN digit = 8 THEN toCHAR = 'eight';
  WHEN digit = 9 THEN toCHAR = 'nine';
ELSE STOP(-29000, 'no digit');
END CASE

If no matching literal or fulfilled search condition exists in a CASE statement, the statement in the ELSE branch is executed.

If there is no ELSE branch, the runtime error -28901 is returned.

See also:

Simple CASE Statement (simple_case_statement)