what am i lacking on mysql select query? - mysql

Question

what am I doing is checking if the signatoryid from the user input has the lowest level from the table which status = 1 and group by tracknum
so if the input of the user is not the lowest level on that tracknum it will not give output. but if it has the lowest level. it will give output
so far this is my query this works for signatoryid-LHPL004
but doesnt work for other signatory id like LHPL003 and so on. so whats lack with mysql code? thank you
SELECT `tracknum`, `signatoryid`, `signatorylevel`, `status`
from tble_transaction
where `status` = "1" and signatoryid = "LHPL004" and `signatorylevel` = (select MIN(`signatorylevel`) from tble_transaction where `status`="1" )
this is my expected output when i use LHPL003 as signatory ID
it didnt print out the one with tracknum DOC009 with signatoryID because the level of LHPL003 is 3 and on that tracknum DOC009 there is someone with lower level whose status is still 1 not 0

Answer 1

Probably you want the corresponding row for each tracknum having the minimum signatorylevel with status=1.
This assumption is based on your comment:
what i want to do sir is show only the ones with the lowest level on
each tracknum which status = 1.
The following query might suffice :
SELECT
tble_transaction.*
FROM tble_transaction
INNER JOIN
(
SELECT
tracknum,
MIN(signatorylevel) min_signatorylevel
FROM tble_transaction
WHERE `status` = "1"
GROUP BY tracknum
) AS t
ON tble_transaction.tracknum = t.tracknum AND
tble_transaction.signatorylevel = t.min_signatorylevel;
Output:
tracknum signatoryid datesigned datereceived signed status signatorylevel
DOC009 LHPL004 0/0/0000 0/0/0000 Released 1 2
DOC010 LHPL003 0/0/0000 0/0/0000 Released 1 3
Demo Here
Note:
Look, in your sample data although minimum signatorylevelis 1 for both tracknum DOC009 AND DOC010 but they have status = 0. So they won't appear in the result.

Answer 2

The subquery
select MIN(signatorylevel) from tble_transaction where status = "1"
returns MIN(signatorylevel) for the entire table. Specifically, it returns the value 2, and only signatoryid LHPL004 has a record with that signatorylevel, according to your sample data.
I think this should work, but I haven't tested it:
SELECT t1.tracknum, t1.signatoryid, t1.signatorylevel, t1.`status`
FROM tble_transaction t1
WHERE t1.`status` = "1"
AND t1.signatoryid = "LHPL004"
AND t1.signatorylevel =
(SELECT MIN(t2.signatorylevel)
FROM tble_transaction t2
WHERE t2.`status` = "1"
AND t2.tracknum = t1.tracknum
);
This solution uses a correlated subquery, where the subquery is run once for each record returned by the outer query. (See the last AND subclause of the subquery's WHERE clause.)
Any correlated subquery can be rewritten as a join, and vice versa, so (assuming your DBMS has a good optimizer) the only significant difference between my solution and 1000111's is personal preference.

Answer 3

Only LHPL004 will generate an output because it is the only one with the lowest signatorylevel and status of 1. Anything else including LHPL003 has not the lowest signatorylevel so it wont output anything and thus your code is working correctly.