select *
from apprenticecourse apc
inner join apprenticeevent  ape on
 (apc.code = ape.code)
 and (apc.item = ape.item)
inner join event  event on
 (ape.event = event.event)
where
 (event.durationtype = 'S')
 and (apc.CourseStartDate -  event.duration+event.priorbuffer >=
'2003-07-08' )
 and (apc.CourseStartDate - event.duration-event.postbuffer <= '2003-07-08')