-- Remember you need run this as two seperate statements.  First delimiter, then the rest.

DELIMITER //;

CREATE PROCEDURE make_intervals(startdate TIMESTAMP, enddate TIMESTAMP, intval INTEGER, unitval VARCHAR(10))
BEGIN
-- *************************************************************************
-- Procedure: make_intervals()
--    Author: Ron Savage
--      Date: 02/03/2009
--
-- Description:
-- This procedure creates a temporary table named time_intervals with the
-- interval_start and interval_end fields specifed from the startdate and
-- enddate arguments, at intervals of intval (unitval) size.
-- *************************************************************************
   DECLARE thisDate TIMESTAMP;
   DECLARE nextDate TIMESTAMP;
   SET thisDate = startdate;

   -- *************************************************************************
   -- Drop / create the temp table
   -- *************************************************************************
   DROP TEMPORARY TABLE IF EXISTS time_intervals;
   CREATE TEMPORARY TABLE IF NOT EXISTS time_intervals
      (
      interval_start TIMESTAMP,
      interval_end TIMESTAMP
      );

   -- *************************************************************************
   -- Loop through the startdate adding each intval interval until enddate
   -- *************************************************************************
   repeat
      SELECT
         CASE unitval
            WHEN 'MICROSECOND' THEN timestampadd(MICROSECOND, intval, thisDate)
            WHEN 'SECOND'      THEN timestampadd(SECOND, intval, thisDate)
            WHEN 'MINUTE'      THEN timestampadd(MINUTE, intval, thisDate)
            WHEN 'HOUR'        THEN timestampadd(HOUR, intval, thisDate)
            WHEN 'DAY'         THEN timestampadd(DAY, intval, thisDate)
            WHEN 'WEEK'        THEN timestampadd(WEEK, intval, thisDate)
            WHEN 'MONTH'       THEN timestampadd(MONTH, intval, thisDate)
            WHEN 'QUARTER'     THEN timestampadd(QUARTER, intval, thisDate)
            WHEN 'YEAR'        THEN timestampadd(YEAR, intval, thisDate)
         END INTO nextDate;

      INSERT INTO time_intervals SELECT thisDate, timestampadd(MICROSECOND, -1, nextDate);
      SET thisDate = nextDate;
   until thisDate >= enddate
   END repeat;

 END//