问如何在SQL中加入4个表？

SELECT  a.pick_id, a.Serial_No, a.Work_Ord_No, a.Lot_No, 
        a.Product_no, a.Plan_Qty, a.Machine_no, a.shift, a.Scan_dt, 
        b.Trml_code,
        case when c.Wire_Type is null then '-' else c.Wire_Type +' '+ c.Wire_Size+' '+c.Wire_Color end as Wire,
        case when d.Mtrl_code is null then '-' else d.Mtrl_code end as Material
FROM pickMaster a JOIN
     pickTerminal b
     ON b.id = a.id JOIN
     pickWire c
     ON c.id = a.id JOIN
     pickInserting d
     ON d.id = a.id