Firebird util$range stored procedure

util_range.sql

-- UTIL$RANGE(start, stop, step)
--
-- This file is in the Public Domain.
-- Firebird selectable stored procedure for producing integer ranges.
-- (Mike Pomraning; 2011-03-30)
--
CREATE EXCEPTION util$err_range_zero_step 'step size may not be zero';
SET TERM !!;
CREATE PROCEDURE util$range("Start" INTEGER, "Stop" INTEGER, "Step" INTEGER)
  RETURNS (i INTEGER) AS
BEGIN
  IF ("Step" > 0) THEN BEGIN
    i = "Start";
    WHILE (i <= "Stop") DO BEGIN
      SUSPEND;
      i = i + "Step";
    END
  END
  ELSE IF ("Step" < 0) THEN BEGIN
    i = "Start";
    WHILE (i >= "Stop") DO
    BEGIN
      SUSPEND;
      i = i + "Step";
    END
  END
  ELSE IF ("Step" = 0) THEN
    EXCEPTION util$err_range_zero_step;
  -- ELSE return empty set
END !!
SET TERM ;!!