Simple CASE Statement (simple_case_statement)

				
<simple_case_statement>::=
  CASE <expression>
    <simple_case_when_clause>... [<case_else_clause>]
  END [CASE]

<simple_case_when_clause>::=
  WHEN <literal>[,...] THEN <statement>;

<case_else_clause>::=
  ELSE <statement>;
			

Explanation

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

In the case of a simple  CASE statement ( simple_case_statement), the expression is compared with the literals. If the expression matches a literal, the associated statement is executed and the CASE statement ends.

Examples

CASE digit

WHEN 0 THEN toCHAR = 'zero';

WHEN 1 THEN toCHAR = 'one';

WHEN 2 THEN toCHAR = 'two';

WHEN 3 THEN toCHAR = 'three';

WHEN 4 THEN toCHAR = 'four';

WHEN 5 THEN toCHAR = 'five';

WHEN 6 THEN toCHAR = 'six';

WHEN 7 THEN toCHAR = 'seven';

WHEN 8 THEN toCHAR = 'eight';

WHEN 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 defined in the ELSE branch is executed.

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