Optomized this query - mysql

Question

Having a structure of 3 tables
Table min consist of matcode,min_qty,jo_no,mr_no
Table min_out_body consist of matcode,out_qty,jo_no,mr_no
Table eu_min_out_body consist of matcode,out_qty,jo_no,mr_no
And data as follow:
[min]
matcode min_qty jo_no mr_no
xxx 100 1A A11
xxx 150 2A A22
[min_out_body]
matcode out_qty jo_no mr_no
xxx 10 1A A11
xxx 60 1A A11
xxx 100 2A A22
[eu_min_out_body]
matcode out_qty jo_no mr_no
xxx 20 1A A11
xxx 50 2A A22
What i am trying to achieve is to have a result:
matcode min_qty jo_no mr_no balance
xxx 100 1A A11 10
xxx 150 2A A22 0
Queried using following code :
SELECT
min.matcode,
min.min_qty,
min.jo_no,
min.mr_no
(min.min_qty-(
select ifnull(sum(out_qty),0)
FROM min_out_body
WHERE matcode=min.matcode
and jo_no=min.jo_no
and mr_no=min.mr_no
)-(
select ifnull(sum(out_qty),0)
FROM eu_min_out_body
WHERE matcode=min.matcode
and jo_no=min.jo_no
and mr_no=min.mr_no
)
) as balance
FROM min
WHERE min.matcode = 'xxx'
and (min.min_qty - (select
ifnull(sum(out_qty),0)
FROM min_out_body
WHERE matcode = min.matcode
and jo_no = min.jo_no
and mr_no = min.mr_no) - (select
ifnull(sum(out_qty),0)
FROM eu_min_out_body
WHERE matcode = min.matcode
and jo_no = min.jo_no
and mr_no = min.mr_no)) > 0
I can get the result, but is there any way to simplify the query and reduce the process time?

Answer 1

I see two options, and depending on the amount of data you are dealing with could perform better than other... The first is easier readability wise but simplifies your WHERE clause and may be what you want to run with..
Wrap your query but only up to the WHERE MAT_CODE qualifier. Let that "PQ" (PreQuery) return everything -- ALL balances. Then from that, just apply WHERE balance > 0 vs your complex balance calculation completed AGAIN in the where clause.
SELECT PQ.*
from
( SELECT
min.matcode,
min.min_qty,
min.jo_no,
min.mr_no
(min.min_qty
- ( select ifnull(sum(out_qty),0)
FROM min_out_body
WHERE min_no = min.min_no
and matcode = min.matcode
and jo_no = min.jo_no
and mr_no = min.mr_no )
- ( select ifnull(sum(out_qty),0)
FROM eu_min_out_body
WHERE min_no=min.min_no
and matcode=min.matcode
and jo_no=min.jo_no
and mr_no=min.mr_no ) ) as balance
FROM
min
WHERE
min.matcode = 'xxx' ) PQ
where
balance > 0
If a larger data set, It looks a little larger since it does pre-aggregate queries ONCE per the "out_body" tables and groups by the components your inner field selects were dealing with. Then LEFT JOIN to those tables. The benefit of this approach is that it doesn't run the inner select sum() on a per record basis, and if you have 1000's of records to go through, might be a bigger time saver for you... especially if its going through MIN_OUT_BODY and EU_MIN_OUT_BODY.
By Left-Join, it's either their or not, and the IFNULL() works the same way, then the WHERE clause is the same simple readable computation of the balance WITHOUT having to requery yet again.
SELECT
min.matcode,
min.min_qty,
min.jo_no,
min.mr_no,
min.min_qty - ifnull( MOB1.out_qty, 0 ) - ifnull( EMOB1.out_qty, 0 ) balance
from
min
LEFT JOIN ( select
mob.matcode,
mob.min_no,
mob.jo_no,
mob.mr_no,
SUM( mob.out_qty ) out_qty
from
min_out_body mob
where
mob.matcode = 'xxx'
group by
mob.matcode,
mob.min_no,
mob.jo_no,
mob.mr_no ) MOB1
ON min.matcode = MOB1.matcode
AND min.min_no = MOB1.min_no
AND min.jo_no = MOB1.jo_no
AND min.mr_no = MOB1.mr_no
LEFT JOIN ( select
Emob.matcode,
Emob.min_no,
Emob.jo_no,
Emob.mr_no,
SUM( Emob.out_qty ) out_qty
from
eu_min_out_body Emob
where
Emob.matcode = 'xxx'
group by
Emob.matcode,
Emob.min_no,
Emob.jo_no,
Emob.mr_no ) EMOB1
ON min.matcode = EMOB1.matcode
AND min.min_no = EMOB1.min_no
AND min.jo_no = EMOB1.jo_no
AND min.mr_no = EMOB1.mr_no
where
min.matcode = 'xxx'
AND min.min_qty - ifnull( MOB1.out_qty, 0 ) - ifnull( EMOB1.out_qty, 0 ) > 0