I have having trouble with the following query. Basically what I want to do is set the IsChanged field to 1 where the PScale is changing FROM or TO A, B or C. Note it is the 4th character of the PScale I am looking at. UPDATE TypedSET Typed.IsChanged = 1,FROM dbo.t_Typed as TypedINNER JOIN dbo.t_Employ emp ON emp.PayN = Typed.PayNINNER JOIN dbo.t_EmploySP esp ON esp.EmployId = emp.IdWHERE ((ISNULL(esp.PScale,'') != '' AND ISNULL(Typed.PScale,'') != '') and (ISNULL(esp.PScale,'') <> ISNULL(Typed.PScale,''))) AND (Substring(esp.PScale,4,1) IN ('A','B','C') OR Substring(Typed.PScale,4,1) IN ('A','B','C'))For Example, The following should set IsChanged to 1: C ----> LK ----> AThe following should NOT:A ----> AC ----> CG -----> DA ----> B