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Single Update Query for.....

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  • A Al_Brown

    Slight modification of Luc's idea:

    UPDATE a INNER JOIN a AS a2 ON a.id = 1+((a2.id-1)^1) SET a.name = a2.name

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    Sanjay K Gupta
    wrote on last edited by
    #8

    No, your query is giving error.. Incorrect syntax near the keyword 'INNER'.

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    • S Sanjay K Gupta

      No, your query is giving error.. Incorrect syntax near the keyword 'INNER'.

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      Al_Brown
      wrote on last edited by
      #9

      Which database system are you using? Try it without the word INNER.

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      • A Al_Brown

        Which database system are you using? Try it without the word INNER.

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        Sanjay K Gupta
        wrote on last edited by
        #10

        SQL Server 2008

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        • S Sanjay K Gupta

          SQL Server 2008

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          Al_Brown
          wrote on last edited by
          #11

          Ah, OK. In that case use:

          UPDATE a SET a.name = a2.name FROM a INNER JOIN a AS a2 ON a.id = 1+((a2.id-1)^1)

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          • A Al_Brown

            Ah, OK. In that case use:

            UPDATE a SET a.name = a2.name FROM a INNER JOIN a AS a2 ON a.id = 1+((a2.id-1)^1)

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            Sanjay K Gupta
            wrote on last edited by
            #12

            Clever Code!! That is what I was for looking for. Thanks. .. But here is id in sequence. Consider the condition when Id column is not present then how could you update Odd row to Next Even Row and Even Row to Previous Odd Row.

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            • S Sanjay K Gupta

              Clever Code!! That is what I was for looking for. Thanks. .. But here is id in sequence. Consider the condition when Id column is not present then how could you update Odd row to Next Even Row and Even Row to Previous Odd Row.

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              Al_Brown
              wrote on last edited by
              #13

              This is just theoretical, right....? You could do something like this:

              UPDATE a SET name = (SELECT TOP 1 a2.name FROM a AS a2
              WHERE a2.id * ((a.id & 1) * 2 - 1) > a.id * ((a.id & 1) * 2 - 1)
              AND (a2.id ^ a.id) & 1 = 1
              ORDER BY a2.id * ((a.id & 1) * 2 - 1))

              But then you're going into Hall Of Shame territory

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              • S Sanjay K Gupta

                create table trns.a(id int,name varchar(20))
                insert into TRNS.a values(1,'A')
                insert into TRNS.a values(2,'B')
                insert into TRNS.a values(3,'C')
                insert into TRNS.a values(4,'D')
                insert into TRNS.a values(5,'E')
                insert into TRNS.a values(6,'F')

                select *from a
                if you run select Query, you will get
                id name

                1 A
                2 B
                3 C
                4 D
                . .
                . .

                Q. I need to Update the above table in single update statement to get result like
                select *from a

                id name

                1 B
                2 A
                3 D
                4 C
                . .
                . .

                Note: I know the solution, So I have put this question under "Clever Code".

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                PIEBALDconsult
                wrote on last edited by
                #14

                You could have made this a Friday Programming Quiz. UPDATE a SET id = CASE WHEN id/2.0=CAST(id/2.0 AS INTEGER) THEN id-1 ELSE id+1 END

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                • S Sanjay K Gupta

                  You have updated the Id. What would you do if there may some more columns like Address and Mobile.... Only Update Name column. The result should be.... Id Address Name --------------------------------------- 1 Address1 B 2 Address2 A 3 Address3 D 4 Address4 C . .... . . .... .

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                  PIEBALDconsult
                  wrote on last edited by
                  #15

                  That was not part of the specification.

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                  • L Luc Pattyn

                    UPDATE trns.a SET id=1+((id-1)^1)

                    :)

                    Luc Pattyn [My Articles] Nil Volentibus Arduum

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                    ian dennis 0
                    wrote on last edited by
                    #16

                    Surely anything to the power of 1 is itself? so (id-1)^1 = id-1

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                    • I ian dennis 0

                      Surely anything to the power of 1 is itself? so (id-1)^1 = id-1

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                      Luc Pattyn
                      wrote on last edited by
                      #17

                      ian dennis wrote:

                      anything to the power of 1 is itself

                      yes

                      ian dennis wrote:

                      so (id-1)^1 = id-1

                      no, that is simply never true in the programming languages I use. Including SQL. :)

                      Luc Pattyn [My Articles] Nil Volentibus Arduum


                      Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.

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