 Select  * from groups where WParentGroup2ID in (
 Select  c.WGroupid from groups c where c.WParentGroup2ID in (
Select  b.WGroupid from groups b where b.WParentGroup2ID in (
select a.WGroupid  from groups a where WGroupTypeId = 26 and  (a.WParentGroup2ID = 0 or a.WParentGroup2ID is null)))
)
 