Requete SQL assez complexe

call make_intervals('2010-01-01 00:00:00','2035-12-31 00:00:00',1,'DAY')

CREATE PROCEDURE make_intervals(startdate timestamp, enddate timestamp, intval integer, unitval varchar(10))
BEGIN
-- *************************************************************************
-- Procedure: make_intervals()
*************************************************************************
   declare thisDate timestamp;
   declare nextDate timestamp;
   set thisDate = startdate;

   -- *************************************************************************
   -- Drop / create the table
*************************************************************************
   drop table if exists time_intervals;
   create table if not exists time_intervals
      (
      interval_start timestamp,
      interval_end timestamp
      );

   -- *************************************************************************
   --Boucle
*************************************************************************
   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;