mysql - Subtract colums from two tables -


there 2 tables need total available quantity 

table t1 +-------------+------------+   | code        | qty        |   +-------------+------------+   |           | 500        |   +-------------+------------+       table t2 +-------------+------------+   | code        | qty        |   +-------------+------------+   |           | 10         |   +-------------+------------+     |           | 20         |   +-------------+------------+

with code result 970 instead of 470:

select   `t1`.`code`,   (ifnull(sum(`t1`.`qty`),0) - ifnull(sum(`t2`.`qty`),0)) totalqty   `t1`   left join `t2` on `t1`.`code` =     `t2`.`code` group   `t1`.`code`

what i'm doing wrong?

check code :)

select code,ifnull(sum(qty),0)-ifnull((select sum(qty) t2 t1.code = code),0) answer t1 group code

i edit answer incase want add condition base on code , prevent returning of null value try bro


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