Oracle - 具有连接条件的外部连接

Question

I have a scenario where I have two tables

ORDER

ORDER_NO
LOCATION
ITEM
QTY_RECEIVED

SHIPMENT

ORDER_NO
LOCATION
ITEM
QTY_RECEIVED

There are cases where ORDER table has a record but SHIPMENT table doesn't

I want all the rows from ORDER table where the qty is not equal to the qty in SHIPMENT table, and that will include the rows which are there in ORDER but not in shipment.

I tried doing by this:

SELECT 
    order_no, item, location, SUM(NVL(QTY_RECEIVED, 0)) 
FROM
    ORDERS ol                     
GROUP BY 
    ORDER_NO, ITEM, LOCATION
HAVING 
    SUM (NVL(ol.QTY_RECEIVED,0)) <>      

    (SELECT SUM(NVL(sk.QTY_RECEIVED, 0))
     FROM shipment s
     WHERE s.order_no = ol.order_no
       AND s.item (+)= ol.item
       AND s.location (+) = ol.location
     GROUP BY s.order_no, s.item, s.location);

But it doesn't give the correct result.

how should I do this?

Answer 1

You need LEFT JOIN in order to return the the results even for the non-existing values of SHIPMENT table :

SELECT ol.order_no, ol.item, ol.location, 
       SUM(NVL(ol.QTY_RECEIVED, 0)) AS "Total Quantity Of Orders",
       SUM (NVL(s.QTY_RECEIVED,0))  AS "Total Quantity Of Shpm." 
  FROM orders ol 
  LEFT JOIN shipment s  
    ON s.order_no = ol.order_no
   AND s.item = ol.item
   AND s.location = ol.location
 GROUP BY ol.order_no, ol.item, ol.location
HAVING SUM (NVL(ol.QTY_RECEIVED,0)) <> SUM (NVL(s.QTY_RECEIVED,0)) 

Answer 2

It seems possible to me that an order could have multiple shipments for the same item. If this is the case, you need a different approach:

select order_no, location, item, sum(o_qty), sum(s_qty)
from ((select order_no, location, item, qty_received as o_qty, 0 as s_qty
       from orders
      ) union all
      (select order_no, location, item, 0 as o_qty, qty_received as s_qty
       from shipment
      )
     ) os
group by order_no, location, item
having sum(o_qty) <> sum(s_qty);