Select COUNT(*)
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Thread: Select COUNT(*)

  1. #1
    Join Date
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    Cool Select COUNT(*)

    hi,
    How can I do to have one SELECT clause returning 1 rows with sum of counted rows in table t1 and T2 ..

    select count(*) from t1
    union all
    select count(*) from t2

  2. #2
    Join Date
    Nov 2002
    Location
    Geneva Switzerland
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    select (select count(*) from t1)+(select count(*) from t2) from dual;
    "The power of instruction is seldom of much efficacy except in those happy dispositions where it is almost superfluous" - Gibbon, quoted by R.P.Feynman

  3. #3
    Join Date
    Aug 2002
    Location
    Colorado Springs
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    or ...

    select sum(rc) from
    (
    select 1 rc from t1
    union all
    select 1 from t2
    )

    Must be a lot of ways of doing this.
    David Aldridge,
    "The Oracle Sponge"

    Senior Manager, Business Intelligence Development
    XM Satellite Radio
    Washington, DC

    Oracle ACE

  4. #4
    Join Date
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    Location
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    Posts
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    Hi slimdave, I think I win on speed - "select count(*)" can use Index Fast Full Scan, "select 1" uses FTS (at least on the 100'000 row table I tried).
    "The power of instruction is seldom of much efficacy except in those happy dispositions where it is almost superfluous" - Gibbon, quoted by R.P.Feynman

  5. #5
    Join Date
    Aug 2002
    Location
    Colorado Springs
    Posts
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    how about ...

    select sum(rc) from
    (
    select count(*) rc from t1
    union all
    select count(*) from t2
    )
    David Aldridge,
    "The Oracle Sponge"

    Senior Manager, Business Intelligence Development
    XM Satellite Radio
    Washington, DC

    Oracle ACE

  6. #6
    Join Date
    Nov 2002
    Location
    Geneva Switzerland
    Posts
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    I still win on key-strokes
    "The power of instruction is seldom of much efficacy except in those happy dispositions where it is almost superfluous" - Gibbon, quoted by R.P.Feynman

  7. #7
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    damn you, Mr DaPi, damn you.

    I win on being-able-to-see-the-execution-plan-through-autotrace!
    David Aldridge,
    "The Oracle Sponge"

    Senior Manager, Business Intelligence Development
    XM Satellite Radio
    Washington, DC

    Oracle ACE

  8. #8
    Join Date
    Nov 2000
    Location
    Baltimore, MD USA
    Posts
    1,339
    Heh.

    I'm with slimdave on this one. Oracle's inexcusable inability to show plans for SELECT-clause sub-SELECTs gives the nod to the UNION implementation.

    - Chris
    Christopher R. Long
    ChrisRLong@HotMail.Com
    But that's just my opinion. I could be wrong

  9. #9
    Join Date
    Aug 2002
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    Colorado Springs
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    Victory Shriek!

    Eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    David Aldridge,
    "The Oracle Sponge"

    Senior Manager, Business Intelligence Development
    XM Satellite Radio
    Washington, DC

    Oracle ACE

  10. #10
    Join Date
    Nov 2002
    Location
    Geneva Switzerland
    Posts
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    Looks like the Yanks are ganging up on me. You two must have done "new math" and are now the ones to find "union all" more intuitive than "+" - I gave up set theory at the axiom of choice.

    Have good one!

    P.S. slimdave, please don't make such a dreadful noise when I'm asleep!
    "The power of instruction is seldom of much efficacy except in those happy dispositions where it is almost superfluous" - Gibbon, quoted by R.P.Feynman

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