select
    TBLB.ITEM_CODE as CODE,
    ITEM_NAME as NAME,
    sum(ORDER_QTY) as SUM_QTY
from
    (
        select
            *
        from
            ORDERS as TBLA_1
        left outer join WAREHOUSE as TBLA_2 on TBLA_1.WH_CODE = TBLA_2.WH_CODE
    ) as TBLA
left outer join
    (
        select
            *
        from
            ORDERS_DTL as TBLB_1
        left outer join ITEM as TBLB_2 on TBLB_1.ITEM_CODE  = TBLB_2.ITEM_CODE 
    
    ) as TBLB
    on TBLA.CUSTORDER_NO = TBLB.ORDER_NO 
group by 1,2