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Information Systems ppl please help

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    Information Systems ppl please help

    Here is a query:

    SELECT DISTINCT J#
    FROM SPJ SPJX
    WHERE NOT EXISTS
    ( SELECT *
    FROM SPJ SPJY
    WHERE EXISTS
    ( SELECT *
    FROM SPJ SPJA
    WHERE SPJA.S'# = 'S1'
    AND SPJA.P# = SPJY.P# )
    AND NOT EXISTS
    ( SELECT *
    FROM SPJ SPJB
    WHERE SPJB.S# = 'S1'
    AND SPJB.P# = SPJY.P#
    AND SPJB.J# = SPJX.J# ) ) ;


    Run on a relation called SPJ (Suppliers Parts projects)...meaning which suppliers provide which parts to which project

    so it had S#,P#,J#,qty attributes.... What the ^%@#$&#$%*@&# does this query return??

    All projects where supplier s1 supplies all the parts to that project??

    http://www3.pak.org/gupshup/smilies/frusty.gif



    #2
    who---me, that's some query http://www3.pak.org/gupshup/smilies/pagal.gif I'll try solving it (but I am quite certain I've forgotten most of what I studied a few months back :hehehttp://www3.pak.org/gupshup/smilies/smile.gif... and will get back to you.

    Comment


      #3
      while yur at it try:

      SELECT DISTINCT J#
      FROM SPJ SPJX
      WHERE NOT EXISTS
      ( SELECT *
      FROM SPJ SPJY
      WHERE EXISTS
      ( SELECT *
      FROM SPJ SPJA
      WHERE SPJA.S# = SPJY.S1
      AND SPJA.P# IN
      ( SELECT P# FROM P
      WHERE COLOR = 'Red' )
      AND NOT EXISTS
      ( SELECT *
      FROM SPJ SPJB
      WHERE SPJB.S# = SPJY.S#
      AND SPJB.J# = SPJX.J# ) ) ) ;


      too.... http://www3.pak.org/gupshup/smilies/frown.gif ....P is the parts entity..p# is the part number.



      [This message has been edited by who---me (edited May 13, 2001).]

      Comment


        #4
        who---me, where did you get such complicated ones from? http://www3.pak.org/gupshup/smilies/mad.gif The ones I got at Uni never went beyond 6-8 lines.

        Comment


          #5
          http://www3.pak.org/gupshup/smilies/crying.gif

          They'r from a lab....and I have do same kind on assignment during the week.

          Its the correlation thats killing me http://www3.pak.org/gupshup/smilies/frusty.gif

          and the double negation........ Mind you...I think both these use double negatives

          feel like throwing up http://www3.pak.org/gupshup/smilies/pukey.gif

          Comment

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