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plz explain

  • June 7, 2007 at 5:03 am

    #120350

    SELECT DISTINCT (a.empsal) FROM EMP A WHERE 1 = (SELECT COUNT (DISTINCT

    (b.empsal)) FROM EMP B WHERE a.empsal<=b.empsal);

    Sanz

  • June 7, 2007 at 5:47 am

    #711376

    This is to find the first maximum salary...this is called corelated subquery..

     

    for each avlue of outer subquery the inner subquery will be evaluated

  • June 8, 2007 at 8:23 am

    #711700

    Thanx for the support

    Sanz

  • June 8, 2007 at 11:07 am

    #711766

    It must be something from a tutorial that is illustrating subqueries (and, possibly, DISTINCT). I can't see that it does anything more than 

      select max(empsal) from emp;

    Tomm Carr
    --
    Version Normal Form -- http://groups.google.com/group/vrdbms

  • June 8, 2007 at 1:11 pm

    #711786

    Nope tomm..The query can do much more than just getting max..

    By replacing 1 with 2 in that query will fetch second maximum,

    By replacing 1 with 3 in that query will fetch Thirdmaximum,

    ..

    ..

    etc..

    Its fairly difficult to get second, third maximums just by using MAX..

     

  • June 11, 2007 at 10:18 am

    #712034

    Sure, but by replacing X with Y in any number of queries, we can have lots of fun. All queries have the potential to act differently if we modify them.

    Maybe, as I said, this was part of a tutorial and subsequent lessons replaced the 1 with 2, 3, etc.--or by a parameter--but as written (and the 1 was hard coded--at least in the post) the query only did one thing.

    Tomm Carr
    --
    Version Normal Form -- http://groups.google.com/group/vrdbms

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