7.6.6. WHILE …​ DO

Used for

Looping constructs

Available in

PSQL

Syntax

WHILE <condition> DO
  <compound_statement>

A WHILE statement implements the looping construct in PSQL. The statement or the block of statements will be executed until the condition returns TRUE. Loops can be nested to any depth.

Example

A procedure calculating the sum of numbers from 1 to I shows how the looping construct is used.

CREATE PROCEDURE SUM_INT (I INTEGER)
RETURNS (S INTEGER)
AS
BEGIN
  s = 0;
  WHILE (i > 0) DO
  BEGIN
    s = s + i;
    i = i - 1;
  END
END

Executing the procedure in isql:

EXECUTE PROCEDURE SUM_INT(4);

the result is:

S
==========
10

See also

IF …​ THEN …​ ELSE, LEAVE, EXIT, FOR SELECT, FOR EXECUTE STATEMENT