I have a self join query that pulls a bill of material 7 levels deep. Here is the SQL:
SELECT tblItemMaster.PartNmbr, tblItemMaster.ItemClass, "1" AS [Level 1], tblBOM.ChildClass, tblBOM.ChildPartNmbr, tblBOM.QtyReq, "2" AS [Level 2], tblBOM_2.ChildClass, tblBOM_2.ChildPartNmbr, tblBOM_2.QtyReq...