I don't know why my following update query doesn't work. I attach my access database with the data table and the query. Thank!
UPDATE MAFs_20_archive AS L INNER JOIN MAFs_20_archive AS H ON (L.State=H.State) AND (L.Segment=H.Segment) AND (L.Favorability=H.Favorabi
lity) AND (L.Tier=H.Tier) SET L.Exp_Date = H.Eff_Date-1, L.Row_Expir_Date = Null
WHERE (((L.Row_Expir_Date) Is Not Null) AND ((L.Eff_Date)<H.Eff_Date) AND ((H.Eff_Date)=DMin("Eff_Da
" & L.State & " ' And Segment=' " & L.Segment & " ' AND Favorability=' " & L.Favorability & " ' AND Tier=' " & L.Tier & " ' AND Eff_Date>#" & L.Eff_Date & "#")));