SQL help needed in removing a sub-query

Question

I have a poorly performing SQL that contains a sub-query that is not co-related. I replaced it with a co-related sub-query but performance got worse. Is there a way to rewrite this SQL by removing the sub-query entirely and replacing it with a join?

Below is a simplified version of the query:

    select distinct tab1.app_id, 
            tab1.name, 
            tab1.stat_cd, 
            tab1.qr 
    from apps tab1 , issues tab2 
    where 
            tab1.app_id = tab2.app_id and 
            tab1.qr = 'm' and 
            tab2.iqr = 'm' and 
            tab1.app_id not in 
            ( 
              select  distinct tab3.app_id 
              from issues tab3 
              where tab3.iqr = 'm' and 
              ( 
                 tab3.i_cd = 'f' or 
                 tab3.i_cd = 'r' or 
                 tab3.i_cd = 'c' 
              ) 
            ) 

Any tip or assistance is appreciated. Thank you.

Answer 1

Not sure how much help this will be, but I would like to hear back on how it does...

SELECT DISTINCT tab1.app_id,
       tab1.name, 
       tab1.stat_cd, 
       tab1.qr
FROM apps tab1
JOIN issues tab2 ON tab1.app_id = tab2.app_id
JOIN ( SELECT DISTINCT app_id AS app_id
       FROM issues
       WHERE iqr = 'm'
         AND ( i_cd = 'f' OR
               i_cd = 'r' OR
               i_cd = 'c'
             ) 
     ) tab3 ON tab1.app_id = tab3.app_id
WHERE tab1.qr = 'm'
  AND tab2.iqr = 'm';

Answer 2

Try this:-

 select distinct tab1.app_id, 
            tab1.name, 
            tab1.stat_cd, 
            tab1.qr 
     from apps tab1
     inner join
     issues tab2 
     on 
     tab1.app_id = tab2.app_id
     left join
     issues tab3 
     on
     tab1.app_id = tab3.app_id
  where     tab1.qr = 'm' and 
            tab2.iqr = 'm' and
            concat(tab3.iqr,tab3.i_cd) not in ('mf','mr','mc)  

Hope this helps:-)

Answer 3

try this

select distinct tab1.app_id, 
        tab1.name, 
        tab1.stat_cd, 
        tab1.qr 
from apps tab1 
inner join issues tab2 on ( tab1.app_id, tab1.qr)= ( tab2.app_id, tab2.iqr) and tab1.qr='m'
where not exists 
( 
          select  * from issues tab3 
          where ( tab1.app_id, tab1.qr)= ( tab3.app_id, tab3.iqr)
          and  tab3.i_cd in ('f', 'r', 'c')
) 

Answer 4

other solution

select distinct tab1.app_id, 
        tab1.name, 
        tab1.stat_cd, 
        tab1.qr 
from apps tab1 
inner join issues tab2 on ( tab1.app_id, tab1.qr)= ( tab2.app_id, tab2.iqr) and tab1.qr='m'
left outer join issues tab3 on ( tab1.app_id, tab1.qr)= ( tab3.app_id, tab3.iqr) and tab3.i_cd in ('f', 'r', 'c') 
where tab3.app_id is null