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Optimization of nested queries

Is there a more optimized way to wirte the below query, if yes how and why !

select e.DSORGUT as AGENCEDSORGUT, e.CDORGFNC as AGENCECDORGFNC, e.NOBRN as AGENCENOBRN,
            f.DSORGUT as AGENCEDSORGUT, f.CDORGFNC as AGENCECDORGFNC, f.NOBRN as AGENCENOBRN,
            g.DSORGUT as AGENCEDSORGUT, g.CDORGFNC as AGENCECDORGFNC, g.NOBRN as AGENCENOBRN
       from SYNOUP e, SYNOUP f, SYNOUP g
       where e.NOINP = (select b.NOINPREL from SYNRIP b, SYNREF c where b.NOINP = c.NOINP and b.CDRIC = 'A' and b.CDRIC IS NOT NULL )
       and f.NOINP = (select b.NOINPREL from SYNRIP b, SYNREF c where b.NOINP = c.NOINP and b.CDRIC = 'D' and b.CDRIC IS NOT NULL )
       and g.NOINP = (select b.NOINPREL from SYNRIP b, SYNREF c where b.NOINP = c.NOINP and b.CDRIC = 'R' and b.CDRIC IS NOT NULL )
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gursheenz2008
Asked:
gursheenz2008
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1 Solution
 
GGuzdziolCommented:

with adr as (
  select 
      max(case when b.CDRIC = 'A' THEN b.NOINPREL else null end) as noinprel_a, 
      max(case when b.CDRIC = 'D' THEN b.NOINPREL else null end) as noinprel_d, 
      max(case when b.CDRIC = 'R' THEN b.NOINPREL else null end) as noinprel_r, 
    from SYNRIP b, SYNREF c 
    where b.NOINP = c.NOINP and b.CDRIC in ('A', 'D', 'R') and b.CDRIC IS NOT NULL
)
select e.DSORGUT as AGENCEDSORGUT, e.CDORGFNC as AGENCECDORGFNC, e.NOBRN as AGENCENOBRN,
            f.DSORGUT as AGENCEDSORGUT, f.CDORGFNC as AGENCECDORGFNC, f.NOBRN as AGENCENOBRN,
            g.DSORGUT as AGENCEDSORGUT, g.CDORGFNC as AGENCECDORGFNC, g.NOBRN as AGENCENOBRN
       from SYNOUP e, SYNOUP f, SYNOUP g, adr
     where e.NOINP = adr.noinprel_a
       and f.NOINP = adr.noinprel_d
       and g.NOINP = adr.noinprel_r

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GGuzdziolCommented:
This techinique is called "Subquery factoring".
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gursheenz2008Author Commented:
Thanks for this !

Please correct my understanding !

1.max(case when b.CDRIC = 'A' THEN b.NOINPREL else null end) as noinprel_a,
 This will take the MAX of NOINPREL if there's a value, else null value.

Why we again need b.CDRIC in ('A', 'D', 'R')?

2. "with"  Clause will treat the result of the query as a temp table(GTT)/ in line view.

3. This is not a PL/SQL block, it's a SQL statement

with adr as ( ... ) select ...
       and g.NOINP = adr.noinprel_r ;

4.When Oracel will drop this temp table(GTT)/ in line view.
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sdstuberCommented:
is noinp a unique key for synoup?
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GGuzdziolCommented:
1. It may make Oracle uses index on that field.
2&4. Results of the query will be put in temporary table in temporary tablespace. Once query is finished space may be reused by other processes.
3. Yes, it's SQL statement: http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_10002.htm#i2077142
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