将子查询变成联接

Question

I have a sub query that is running extremely slow but I can't figure out how to write it as a join to speed it up. The subquery is below the AND OR section in the WHERE clause.

select 'Fall ' || (x.syrsdhe_year - 1) "Term",
       count(x.syrsdhe_ssn_id) "Cohort",
       (sum((select '1' from dual where r1.syrsdhe_year = (x.syrsdhe_year))) /         count(x.syrsdhe_ssn_id))*100  "Fall_to_Spring",
       (sum((select '1' from dual where r2.syrsdhe_year = (x.syrsdhe_year + 1))) / count(x.syrsdhe_ssn_id))*100   "One_Year",
       (sum((select '1' from dual where r3.syrsdhe_year = (x.syrsdhe_year + 2))) / count(x.syrsdhe_ssn_id))*100   "Two_Year"

from irdeptq.syrsdhe x
 left join irdeptq.syrsdhe r1
        on r1.syrsdhe_ssn_id = x.syrsdhe_ssn_id
       and r1.syrsdhe_term = '2'
       and r1.syrsdhe_student_level in ('01','02','03','04')
       and r1.syrsdhe_year = (x.syrsdhe_year)
left join irdeptq.syrsdhe r2
        on r2.syrsdhe_ssn_id = x.syrsdhe_ssn_id
       and r2.syrsdhe_term = '1'
       and r2.syrsdhe_student_level in ('01','02','03','04')
       and r2.syrsdhe_year = (x.syrsdhe_year + 1)
left join irdeptq.syrsdhe r3
        on r3.syrsdhe_ssn_id = x.syrsdhe_ssn_id
        and r3.syrsdhe_term = '1'
        and r3.syrsdhe_student_level in ('01','02','03','04')
        and r3.syrsdhe_year = (x.syrsdhe_year + 2)



where x.syrsdhe_enroll_status = '01'
  and x.syrsdhe_attend_status = '0'
  and x.syrsdhe_degree_intent != '3'
  and x.syrsdhe_term = '1'
  and x.syrsdhe_year  >=  '2006'
  and x.syrsdhe_housing is not null
  and ((x.syrsdhe_year = '2006' and x.syrsdhe_pidm not in (select sgrchrt_pidm from sgrchrt where sgrchrt_term_code_eff = x.syrsdhe_banner_term and sgrchrt_chrt_code in ('HRC','SRC')))
   or (x.syrsdhe_year = '2007' and x.syrsdhe_pidm not in (select sgrchrt_pidm from sgrchrt where sgrchrt_term_code_eff = x.syrsdhe_banner_term and sgrchrt_chrt_code in ('HRC','SRC','SDRC')))
   or (x.syrsdhe_year = '2008' and x.syrsdhe_pidm not in (select sgrchrt_pidm from sgrchrt where sgrchrt_term_code_eff = x.syrsdhe_banner_term and sgrchrt_chrt_code in ('HRC','SRC','SDRC')))
   or (x.syrsdhe_year = '2009' and x.syrsdhe_pidm not in (select sgrchrt_pidm from sgrchrt where sgrchrt_term_code_eff = x.syrsdhe_banner_term and sgrchrt_chrt_code in ('HRC','SRC','SDRC')))
   or (x.syrsdhe_year = '2010' and x.syrsdhe_pidm not in (select sgrchrt_pidm from sgrchrt where sgrchrt_term_code_eff = x.syrsdhe_banner_term and sgrchrt_chrt_code in ('HRC','SRC','SDRC')))
   or (x.syrsdhe_year = '2011' and x.syrsdhe_pidm not in (select sgrchrt_pidm from sgrchrt where sgrchrt_term_code_eff = x.syrsdhe_banner_term and sgrchrt_chrt_code in ('HRC','SRC','SDRC','STEM')))
   or (x.syrsdhe_year = '2012' and x.syrsdhe_pidm not in (select sgrchrt_pidm from sgrchrt where sgrchrt_term_code_eff = x.syrsdhe_banner_term and sgrchrt_chrt_code in ('HRC','SDRC','STEM','EDGE')))
   or (x.syrsdhe_year = '2013' and x.syrsdhe_pidm not in (select sgrchrt_pidm from sgrchrt where sgrchrt_term_code_eff = x.syrsdhe_banner_term and sgrchrt_chrt_code in ('HRC','STEM','EDGE','STARS')))
   )
  **and x.syrsdhe_pidm not in (select rpratrm_pidm
                         from rpratrm where x.syrsdhe_banner_term = rpratrm_term_code
                         and x.syrsdhe_pidm = rpratrm_pidm
                         and rpratrm_paid_amt >0
                         and rpratrm_fund_code in ('HCSCH','HCFADJ','HCFULL','HCPRRM','HCBSCH','HCSUPP'))**


  Group By 'Fall ' || (X.Syrsdhe_Year - 1)
  order By 'Fall ' || (X.Syrsdhe_Year - 1) 

I've tested the subquery alone and it pulls the neccessary PIDMS lighting quick but as soon as I write it as a subquery it slows the entire query down. I've had this problem multiple times in the past so if anyone knows the logic behind it that would be helpful.

DBMS - ORACLE

Answer 1

The usual way to turn NOT IN into a JOIN is this:

SELECT whatever
FROM table1
WHERE somecol NOT IN (SELECT othercol FROM ...)

is:

SELECT whatever
FROM table1
LEFT JOIN (SELECT othercol FROM ...) t2 ON somecol = othercol
WHERE othercol IS NULL

Depending on the structure of the subquery, it may be possible to move its WHERE clauses into the ON clause of the JOIN, eg

SELECT whatever
FROM table1
LEFT JOIN table2 ON somecol = othercol AND table2.date > '2013-04-01'

If the subquery can have multiple matches for rows in table1 , you should use SELECT DISTINCT in the subquery to prevent duplicates from appearing in the result.

Answer 2

First, you seem to have an extra table1 in the from clause. This is probably causing your problems. Consider this instead:

table1_id not in (select table2_id
                             from table2
                             where table1.table1_term = table2_term
                             and table2_paid_amt >0
                             )

The following converts this version to a left outer join . The where clause then does the "not exists" part of the query:

select . . .
from table1 t1 left outer join
     table2 t2
     on t1.table1_term = t2.table2_term and
        t2.table2_paid_amt > 0
where t2.table2_id is null