从两个不同的表中添加总和值

Question

How can i achieve this. T2 is linked with another table which contains order details like customer name, country and classification. They have an inner join.

T1 is linked to T2 only via order code and order item.

Answer 1

Assuming that both tables report the same set of order numbers, we can try joining two subqueries each of which finds the sums in the respective tables:

SELECT
    t1.ORDER_NUM,
    t1.ORDER_ITEM,
    t1.PRODUCED + t2.PRODUCED AS PRODUCED
FROM
(
    SELECT ORDER_NUM, ORDER_ITEM, SUM(PRODUCED) AS PRODUCED
    FROM table1
    GROUP BY ORDER_NUM
) t1
INNER JOIN
(
    SELECT ORDER_NUM, ORDER_ITEM, SUM(NET_IN - NET_OUT) AS PRODUCED
    FROM table2
    GROUP BY ORDER_NUM
) t2
    ON t1.ORDER_NUM = t2.ORDER_NUM AND
       t1.ORDER_ITEM = t2.ORDER_ITEM
ORDER BY
    t1.ORDER_NUM,
    t1.ORDER_ITEM;

Note that the above is not necessarily an ideal approach, because a given order/item combination in one table might not appear in the other table. A better approach would be to start the query with a reference table containing all orders and items. That failing, we could convert the above to a full outer join.

Answer 2

I think a simple approach is union all :

select ordernum, orderitem, sum(produced) as produced
from ((select ordernum, orderitem, produced
       from table1
      ) union all
      (select ordernum, orderitem, netout
       from table2
      )
     ) t12
group by ordernum, orderitem;

This has two advantages over pre-aggregating and using join s:

1. It keeps all order/item pairs, even those that appear in one table.
2. If you add a where claus to the outer query, SQL Server is likely to "project" that into the subqueries.

Answer 3

Try for bellow query also

select t1.order_num,t1.order_item,sum(t1.produced)+(select sum(net_in) from t2)-(select sum(t2.net_out) from t2)PRODUCED
from t1 
group by t1.order_num,t1.order_item

if you have wanted the only sum from another table that time you have used select query and do the sum of a particular column.