Kelly, > it gave me something to google using > > i settled on: > > select t.plantkey, t.mostrecent, t.tagnumber, t.datetested, t.equipmentkey > from reliefd t where t.mostrecent='T' and > t.PlantKey='20030319103909097704' and exists (select 1 from reliefd p > where p.datetested<='2005' and t.equipmentkey = p.equipmentkey) order > by t.tagnumber > > that returns the result i need and i think the > > exists ( select 1....) is the most efficient > > thoughts?
EXISTS will ** be faster** that IN (SELECT ... FROM ...) in 98% of cases -- it depends on the size of the target table. But if the IN clause has defined list of values, up 1500 in the case of Windows builds, [eg. IN (1,2,3,4, ...)] the answer is not as "black and white" but will likely favor the defined list IN syntax. Sean
