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  4. OR in a JOIN

OR in a JOIN

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  • L Luc Pattyn

    Ah, I didn't know logic operators were allowed in the ON clause, but as they are, why not just exploit them to the fullest:

    SELECT *
    FROM TableA A
    INNER JOIN TableB B
    ON A.Field1=B.Field1
    OR (A.Field1<>B.Field1 AND A.Field2=B.Field2)

    Maybe now is the time for a :java:?

    Luc Pattyn [My Articles] Nil Volentibus Arduum

    P Offline
    P Offline
    PIEBALDconsult
    wrote on last edited by
    #7

    :doh: The :java: hadn't worked. Neither did the tequila. Trying it now... Edit: No, that doesn't work -- because there are two different rows.

    P 1 Reply Last reply
    0
    • P PIEBALDconsult

      :doh: The :java: hadn't worked. Neither did the tequila. Trying it now... Edit: No, that doesn't work -- because there are two different rows.

      P Offline
      P Offline
      Paul Conrad
      wrote on last edited by
      #8

      Do you have a sample data set that you are using?

      ""Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

      P 1 Reply Last reply
      0
      • P PIEBALDconsult

        I'm having some trouble with a JOIN that involves an OR (in SQL Server). For example:

        SELECT *
        FROM TableA A
        INNER JOIN TableB B
        ON A.Field1=B.Field1
        OR A.Field2=B.Field2

        Quite correctly this produces two output rows for each row in TableA that matches TableB via both Field1 and Field2* -- but for this JOIN I want to output only one row when both match (preferably the result of the Field1 match, and only report the Field2 match if Field1 doesn't match). * Clarification -- when it matches two rows in TableB; one via Field1 and the other via Field2. I haven't done much searching for pointers because I don't think it's possible, however I'm posting here just in case someone here knows of a way or a simple (SQL only) work-around. Edit -- Here's an example:

        SELECT * FROM TableA

        ID Field1 Field2


        10 A E
        11 E D
        12 A D

        SELECT * FROM TableB

        ID Field1 Field2


        20 A B
        21 C D

        10 will match only 20 ; 11 will match only 21 ; 12 will match both 20 and 21 -- so I want 20.

        ID Field1 Field2 ID Field1 Field2
        10 A E 20 A B <-- I want this row
        11 E D 21 C D <-- I want this row
        12 A D 20 A B <-- I want this row
        12 A D 21 C D <-- I don't want this row

        Luc's and pmpdesign's suggestions yield the same output. Here's a variation of Bernhard's suggestion, which seems to work:

        WITH cte1 AS
        (
        SELECT A.ID aID
        , A.Field1 aField1
        , A.Field2 aField2
        , B.ID bID
        , B.Field1 bField1
        , B.Field2 bField2
        FROM TableA A
        INNER JOIN TableB B
        ON A.Field1=B.Field1
        )
        , cte2 AS
        (
        SELECT A.ID aID
        , A.Field1 aField1
        , A.Field2 aField2
        , B.ID bID
        , B.Field1 bField1
        , B.Field2 bField2
        FROM TableA A
        INNER JOIN TableB B
        ON A.Field2=B.Field2
        )
        SELECT *
        FROM cte1
        UNION ALL
        SELECT C2.*
        FROM cte2 C2
        LEFT OUTER JOIN cte1 C1
        ON C2.aID=C1.aID
        WHERE C1.aID IS NULL

        P Offline
        P Offline
        pmpdesign
        wrote on last edited by
        #9

        Without a dataset I can't be sure, but have you tried

        SELECT DISTINCT * FROM...

        P 1 Reply Last reply
        0
        • P PIEBALDconsult

          I'm having some trouble with a JOIN that involves an OR (in SQL Server). For example:

          SELECT *
          FROM TableA A
          INNER JOIN TableB B
          ON A.Field1=B.Field1
          OR A.Field2=B.Field2

          Quite correctly this produces two output rows for each row in TableA that matches TableB via both Field1 and Field2* -- but for this JOIN I want to output only one row when both match (preferably the result of the Field1 match, and only report the Field2 match if Field1 doesn't match). * Clarification -- when it matches two rows in TableB; one via Field1 and the other via Field2. I haven't done much searching for pointers because I don't think it's possible, however I'm posting here just in case someone here knows of a way or a simple (SQL only) work-around. Edit -- Here's an example:

          SELECT * FROM TableA

          ID Field1 Field2


          10 A E
          11 E D
          12 A D

          SELECT * FROM TableB

          ID Field1 Field2


          20 A B
          21 C D

          10 will match only 20 ; 11 will match only 21 ; 12 will match both 20 and 21 -- so I want 20.

          ID Field1 Field2 ID Field1 Field2
          10 A E 20 A B <-- I want this row
          11 E D 21 C D <-- I want this row
          12 A D 20 A B <-- I want this row
          12 A D 21 C D <-- I don't want this row

          Luc's and pmpdesign's suggestions yield the same output. Here's a variation of Bernhard's suggestion, which seems to work:

          WITH cte1 AS
          (
          SELECT A.ID aID
          , A.Field1 aField1
          , A.Field2 aField2
          , B.ID bID
          , B.Field1 bField1
          , B.Field2 bField2
          FROM TableA A
          INNER JOIN TableB B
          ON A.Field1=B.Field1
          )
          , cte2 AS
          (
          SELECT A.ID aID
          , A.Field1 aField1
          , A.Field2 aField2
          , B.ID bID
          , B.Field1 bField1
          , B.Field2 bField2
          FROM TableA A
          INNER JOIN TableB B
          ON A.Field2=B.Field2
          )
          SELECT *
          FROM cte1
          UNION ALL
          SELECT C2.*
          FROM cte2 C2
          LEFT OUTER JOIN cte1 C1
          ON C2.aID=C1.aID
          WHERE C1.aID IS NULL

          B Offline
          B Offline
          Bernhard Hiller
          wrote on last edited by
          #10

          A complicated UNION:

          SELECT *
          FROM TableA A
          INNER JOIN TableB B
          ON A.Field1=B.Field1
          UNION
          SELECT *
          FROM TableA A
          INNER JOIN TableB B
          ON A.Field2=B.Field2
          WHERE A.ID NOT IN
          (
          SELECT ID
          FROM TableA A
          INNER JOIN TableB B
          ON A.Field1=B.Field1
          )

          assuming that ID is the primary key of TableA.

          P 1 Reply Last reply
          0
          • P pmpdesign

            Without a dataset I can't be sure, but have you tried

            SELECT DISTINCT * FROM...

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            P Offline
            PIEBALDconsult
            wrote on last edited by
            #11

            No, that won't work -- the two resultant rows are distinct.

            1 Reply Last reply
            0
            • B Bernhard Hiller

              A complicated UNION:

              SELECT *
              FROM TableA A
              INNER JOIN TableB B
              ON A.Field1=B.Field1
              UNION
              SELECT *
              FROM TableA A
              INNER JOIN TableB B
              ON A.Field2=B.Field2
              WHERE A.ID NOT IN
              (
              SELECT ID
              FROM TableA A
              INNER JOIN TableB B
              ON A.Field1=B.Field1
              )

              assuming that ID is the primary key of TableA.

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              PIEBALDconsult
              wrote on last edited by
              #12

              Possibly, but no, no primary key. Tried it, and it seems to work. :thumbsup: It may take a while to run on the data though. :sigh:

              1 Reply Last reply
              0
              • P Paul Conrad

                Do you have a sample data set that you are using?

                ""Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

                P Offline
                P Offline
                PIEBALDconsult
                wrote on last edited by
                #13

                I'll cobble something up.

                P 1 Reply Last reply
                0
                • P PIEBALDconsult

                  I'm having some trouble with a JOIN that involves an OR (in SQL Server). For example:

                  SELECT *
                  FROM TableA A
                  INNER JOIN TableB B
                  ON A.Field1=B.Field1
                  OR A.Field2=B.Field2

                  Quite correctly this produces two output rows for each row in TableA that matches TableB via both Field1 and Field2* -- but for this JOIN I want to output only one row when both match (preferably the result of the Field1 match, and only report the Field2 match if Field1 doesn't match). * Clarification -- when it matches two rows in TableB; one via Field1 and the other via Field2. I haven't done much searching for pointers because I don't think it's possible, however I'm posting here just in case someone here knows of a way or a simple (SQL only) work-around. Edit -- Here's an example:

                  SELECT * FROM TableA

                  ID Field1 Field2


                  10 A E
                  11 E D
                  12 A D

                  SELECT * FROM TableB

                  ID Field1 Field2


                  20 A B
                  21 C D

                  10 will match only 20 ; 11 will match only 21 ; 12 will match both 20 and 21 -- so I want 20.

                  ID Field1 Field2 ID Field1 Field2
                  10 A E 20 A B <-- I want this row
                  11 E D 21 C D <-- I want this row
                  12 A D 20 A B <-- I want this row
                  12 A D 21 C D <-- I don't want this row

                  Luc's and pmpdesign's suggestions yield the same output. Here's a variation of Bernhard's suggestion, which seems to work:

                  WITH cte1 AS
                  (
                  SELECT A.ID aID
                  , A.Field1 aField1
                  , A.Field2 aField2
                  , B.ID bID
                  , B.Field1 bField1
                  , B.Field2 bField2
                  FROM TableA A
                  INNER JOIN TableB B
                  ON A.Field1=B.Field1
                  )
                  , cte2 AS
                  (
                  SELECT A.ID aID
                  , A.Field1 aField1
                  , A.Field2 aField2
                  , B.ID bID
                  , B.Field1 bField1
                  , B.Field2 bField2
                  FROM TableA A
                  INNER JOIN TableB B
                  ON A.Field2=B.Field2
                  )
                  SELECT *
                  FROM cte1
                  UNION ALL
                  SELECT C2.*
                  FROM cte2 C2
                  LEFT OUTER JOIN cte1 C1
                  ON C2.aID=C1.aID
                  WHERE C1.aID IS NULL

                  C Offline
                  C Offline
                  Chris Meech
                  wrote on last edited by
                  #14

                  To have the duplicates removed, I think a union would do that.

                  SELECT *
                  FROM TableA A
                  INNER JOIN TableB B
                  ON A.Field1=B.Field1
                  UNION
                  SELECT *
                  FROM TableA A
                  INNER JOIN TableB B
                  ON A.Field1<>B.Field1 AND A.Field2=B.Field2
                  ;

                  Try that. :)

                  Chris Meech I am Canadian. [heard in a local bar] In theory there is no difference between theory and practice. In practice there is. [Yogi Berra] posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]

                  P 1 Reply Last reply
                  0
                  • C Chris Meech

                    To have the duplicates removed, I think a union would do that.

                    SELECT *
                    FROM TableA A
                    INNER JOIN TableB B
                    ON A.Field1=B.Field1
                    UNION
                    SELECT *
                    FROM TableA A
                    INNER JOIN TableB B
                    ON A.Field1<>B.Field1 AND A.Field2=B.Field2
                    ;

                    Try that. :)

                    Chris Meech I am Canadian. [heard in a local bar] In theory there is no difference between theory and practice. In practice there is. [Yogi Berra] posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]

                    P Offline
                    P Offline
                    PIEBALDconsult
                    wrote on last edited by
                    #15

                    I think that's basically what Luc suggested -- and it doesn't work.

                    C 1 Reply Last reply
                    0
                    • P PIEBALDconsult

                      I think that's basically what Luc suggested -- and it doesn't work.

                      C Offline
                      C Offline
                      Chris Meech
                      wrote on last edited by
                      #16

                      It's similar to what other's have suggested except that it's a union of the two result sets, which should eliminate any duplicates.

                      Chris Meech I am Canadian. [heard in a local bar] In theory there is no difference between theory and practice. In practice there is. [Yogi Berra] posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]

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                      0
                      • P PIEBALDconsult

                        I'll cobble something up.

                        P Offline
                        P Offline
                        Paul Conrad
                        wrote on last edited by
                        #17

                        If it is possible, that would be cool so there can be a data set to test against and see what the expected results are :)

                        ""Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

                        P 1 Reply Last reply
                        0
                        • C Chris Meech

                          It's similar to what other's have suggested except that it's a union of the two result sets, which should eliminate any duplicates.

                          Chris Meech I am Canadian. [heard in a local bar] In theory there is no difference between theory and practice. In practice there is. [Yogi Berra] posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]

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                          P Offline
                          PIEBALDconsult
                          wrote on last edited by
                          #18

                          Chris Meech wrote:

                          should eliminate any duplicates.

                          Except it doesn't. I have added some clarification and sample data to my post.

                          C 1 Reply Last reply
                          0
                          • P Paul Conrad

                            If it is possible, that would be cool so there can be a data set to test against and see what the expected results are :)

                            ""Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

                            P Offline
                            P Offline
                            PIEBALDconsult
                            wrote on last edited by
                            #19

                            I added it to the post with some clarification.

                            P 1 Reply Last reply
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                            • P PIEBALDconsult

                              I added it to the post with some clarification.

                              P Offline
                              P Offline
                              Paul Conrad
                              wrote on last edited by
                              #20

                              Coolness! I will check it out soon and see if there's anything I can add to this thread in terms of a solution :)

                              ""Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

                              1 Reply Last reply
                              0
                              • P PIEBALDconsult

                                I'm having some trouble with a JOIN that involves an OR (in SQL Server). For example:

                                SELECT *
                                FROM TableA A
                                INNER JOIN TableB B
                                ON A.Field1=B.Field1
                                OR A.Field2=B.Field2

                                Quite correctly this produces two output rows for each row in TableA that matches TableB via both Field1 and Field2* -- but for this JOIN I want to output only one row when both match (preferably the result of the Field1 match, and only report the Field2 match if Field1 doesn't match). * Clarification -- when it matches two rows in TableB; one via Field1 and the other via Field2. I haven't done much searching for pointers because I don't think it's possible, however I'm posting here just in case someone here knows of a way or a simple (SQL only) work-around. Edit -- Here's an example:

                                SELECT * FROM TableA

                                ID Field1 Field2


                                10 A E
                                11 E D
                                12 A D

                                SELECT * FROM TableB

                                ID Field1 Field2


                                20 A B
                                21 C D

                                10 will match only 20 ; 11 will match only 21 ; 12 will match both 20 and 21 -- so I want 20.

                                ID Field1 Field2 ID Field1 Field2
                                10 A E 20 A B <-- I want this row
                                11 E D 21 C D <-- I want this row
                                12 A D 20 A B <-- I want this row
                                12 A D 21 C D <-- I don't want this row

                                Luc's and pmpdesign's suggestions yield the same output. Here's a variation of Bernhard's suggestion, which seems to work:

                                WITH cte1 AS
                                (
                                SELECT A.ID aID
                                , A.Field1 aField1
                                , A.Field2 aField2
                                , B.ID bID
                                , B.Field1 bField1
                                , B.Field2 bField2
                                FROM TableA A
                                INNER JOIN TableB B
                                ON A.Field1=B.Field1
                                )
                                , cte2 AS
                                (
                                SELECT A.ID aID
                                , A.Field1 aField1
                                , A.Field2 aField2
                                , B.ID bID
                                , B.Field1 bField1
                                , B.Field2 bField2
                                FROM TableA A
                                INNER JOIN TableB B
                                ON A.Field2=B.Field2
                                )
                                SELECT *
                                FROM cte1
                                UNION ALL
                                SELECT C2.*
                                FROM cte2 C2
                                LEFT OUTER JOIN cte1 C1
                                ON C2.aID=C1.aID
                                WHERE C1.aID IS NULL

                                P Offline
                                P Offline
                                Paul Conrad
                                wrote on last edited by
                                #21

                                PIEBALDconsult wrote:

                                so I want 20

                                Do you want 20 in both rows with the Id from Table A being 10, and 12?

                                ""Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

                                P 1 Reply Last reply
                                0
                                • P PIEBALDconsult

                                  Chris Meech wrote:

                                  should eliminate any duplicates.

                                  Except it doesn't. I have added some clarification and sample data to my post.

                                  C Offline
                                  C Offline
                                  Chris Meech
                                  wrote on last edited by
                                  #22

                                  It will remove the duplicates of the resultant set, but now that I've read your example, that is not quite what you are after. In your example once the row with ID 12 from table A matched on FieldA for the row with ID 20, you don't want to include it anymore where it might match on FieldB.

                                  Chris Meech I am Canadian. [heard in a local bar] In theory there is no difference between theory and practice. In practice there is. [Yogi Berra] posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]

                                  1 Reply Last reply
                                  0
                                  • P Paul Conrad

                                    PIEBALDconsult wrote:

                                    so I want 20

                                    Do you want 20 in both rows with the Id from Table A being 10, and 12?

                                    ""Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

                                    P Offline
                                    P Offline
                                    PIEBALDconsult
                                    wrote on last edited by
                                    #23

                                    Yes.

                                    1 Reply Last reply
                                    0
                                    • P PIEBALDconsult

                                      I'm having some trouble with a JOIN that involves an OR (in SQL Server). For example:

                                      SELECT *
                                      FROM TableA A
                                      INNER JOIN TableB B
                                      ON A.Field1=B.Field1
                                      OR A.Field2=B.Field2

                                      Quite correctly this produces two output rows for each row in TableA that matches TableB via both Field1 and Field2* -- but for this JOIN I want to output only one row when both match (preferably the result of the Field1 match, and only report the Field2 match if Field1 doesn't match). * Clarification -- when it matches two rows in TableB; one via Field1 and the other via Field2. I haven't done much searching for pointers because I don't think it's possible, however I'm posting here just in case someone here knows of a way or a simple (SQL only) work-around. Edit -- Here's an example:

                                      SELECT * FROM TableA

                                      ID Field1 Field2


                                      10 A E
                                      11 E D
                                      12 A D

                                      SELECT * FROM TableB

                                      ID Field1 Field2


                                      20 A B
                                      21 C D

                                      10 will match only 20 ; 11 will match only 21 ; 12 will match both 20 and 21 -- so I want 20.

                                      ID Field1 Field2 ID Field1 Field2
                                      10 A E 20 A B <-- I want this row
                                      11 E D 21 C D <-- I want this row
                                      12 A D 20 A B <-- I want this row
                                      12 A D 21 C D <-- I don't want this row

                                      Luc's and pmpdesign's suggestions yield the same output. Here's a variation of Bernhard's suggestion, which seems to work:

                                      WITH cte1 AS
                                      (
                                      SELECT A.ID aID
                                      , A.Field1 aField1
                                      , A.Field2 aField2
                                      , B.ID bID
                                      , B.Field1 bField1
                                      , B.Field2 bField2
                                      FROM TableA A
                                      INNER JOIN TableB B
                                      ON A.Field1=B.Field1
                                      )
                                      , cte2 AS
                                      (
                                      SELECT A.ID aID
                                      , A.Field1 aField1
                                      , A.Field2 aField2
                                      , B.ID bID
                                      , B.Field1 bField1
                                      , B.Field2 bField2
                                      FROM TableA A
                                      INNER JOIN TableB B
                                      ON A.Field2=B.Field2
                                      )
                                      SELECT *
                                      FROM cte1
                                      UNION ALL
                                      SELECT C2.*
                                      FROM cte2 C2
                                      LEFT OUTER JOIN cte1 C1
                                      ON C2.aID=C1.aID
                                      WHERE C1.aID IS NULL

                                      L Offline
                                      L Offline
                                      Luc Pattyn
                                      wrote on last edited by
                                      #24

                                      Your modified message is much clearer. And this is what works for me:

                                      SELECT * FROM TableA A INNER JOIN TableB B ON A.Field1=B.Field1
                                      UNION ALL
                                      SELECT * FROM TableA A INNER JOIN TableB B ON A.Field2=B.Field2
                                      WHERE NOT A.ID IN (SELECT A.ID FROM TableA A INNER JOIN TableB B ON A.Field1=B.Field1)

                                      just 3 SELECTs, no LEFT PS: I failed to get it to work with a CTE on SQL Server... :)

                                      Luc Pattyn [My Articles] Nil Volentibus Arduum

                                      B 1 Reply Last reply
                                      0
                                      • P PIEBALDconsult

                                        I'm having some trouble with a JOIN that involves an OR (in SQL Server). For example:

                                        SELECT *
                                        FROM TableA A
                                        INNER JOIN TableB B
                                        ON A.Field1=B.Field1
                                        OR A.Field2=B.Field2

                                        Quite correctly this produces two output rows for each row in TableA that matches TableB via both Field1 and Field2* -- but for this JOIN I want to output only one row when both match (preferably the result of the Field1 match, and only report the Field2 match if Field1 doesn't match). * Clarification -- when it matches two rows in TableB; one via Field1 and the other via Field2. I haven't done much searching for pointers because I don't think it's possible, however I'm posting here just in case someone here knows of a way or a simple (SQL only) work-around. Edit -- Here's an example:

                                        SELECT * FROM TableA

                                        ID Field1 Field2


                                        10 A E
                                        11 E D
                                        12 A D

                                        SELECT * FROM TableB

                                        ID Field1 Field2


                                        20 A B
                                        21 C D

                                        10 will match only 20 ; 11 will match only 21 ; 12 will match both 20 and 21 -- so I want 20.

                                        ID Field1 Field2 ID Field1 Field2
                                        10 A E 20 A B <-- I want this row
                                        11 E D 21 C D <-- I want this row
                                        12 A D 20 A B <-- I want this row
                                        12 A D 21 C D <-- I don't want this row

                                        Luc's and pmpdesign's suggestions yield the same output. Here's a variation of Bernhard's suggestion, which seems to work:

                                        WITH cte1 AS
                                        (
                                        SELECT A.ID aID
                                        , A.Field1 aField1
                                        , A.Field2 aField2
                                        , B.ID bID
                                        , B.Field1 bField1
                                        , B.Field2 bField2
                                        FROM TableA A
                                        INNER JOIN TableB B
                                        ON A.Field1=B.Field1
                                        )
                                        , cte2 AS
                                        (
                                        SELECT A.ID aID
                                        , A.Field1 aField1
                                        , A.Field2 aField2
                                        , B.ID bID
                                        , B.Field1 bField1
                                        , B.Field2 bField2
                                        FROM TableA A
                                        INNER JOIN TableB B
                                        ON A.Field2=B.Field2
                                        )
                                        SELECT *
                                        FROM cte1
                                        UNION ALL
                                        SELECT C2.*
                                        FROM cte2 C2
                                        LEFT OUTER JOIN cte1 C1
                                        ON C2.aID=C1.aID
                                        WHERE C1.aID IS NULL

                                        J Online
                                        J Online
                                        Jorgen Andersson
                                        wrote on last edited by
                                        #25

                                        Here's another way to do it:

                                        WITH CTE AS
                                        (
                                        SELECT A.ID aID
                                        ,A.Field1 aField1
                                        ,A.Field2 aField2
                                        ,CASE WHEN L.ID IS NULL THEN R.ID ELSE L.ID end bID
                                        ,CASE WHEN L.Field1 IS NULL THEN R.field1 ELSE L.Field1 END bField1
                                        ,CASE WHEN L.Field2 IS NULL THEN R.Field2 ELSE L.Field2 END bField2
                                        FROM TableB L
                                        right OUTER JOIN TableA A
                                        ON l.field1 = a.field1
                                        left OUTER JOIN TableB R
                                        ON a.field2 = r.field2
                                        )
                                        SELECT aID
                                        ,aField1
                                        ,aField2
                                        ,bID
                                        ,bField1
                                        ,bField2
                                        FROM CTE
                                        WHERE bid IS NOT null

                                        The plan indicates that it should be faster, but that's with dummy data. I'm curious about the performance with real data.

                                        Light moves faster than sound. That is why some people appear bright, until you hear them speak. List of common misconceptions

                                        L 1 Reply Last reply
                                        0
                                        • J Jorgen Andersson

                                          Here's another way to do it:

                                          WITH CTE AS
                                          (
                                          SELECT A.ID aID
                                          ,A.Field1 aField1
                                          ,A.Field2 aField2
                                          ,CASE WHEN L.ID IS NULL THEN R.ID ELSE L.ID end bID
                                          ,CASE WHEN L.Field1 IS NULL THEN R.field1 ELSE L.Field1 END bField1
                                          ,CASE WHEN L.Field2 IS NULL THEN R.Field2 ELSE L.Field2 END bField2
                                          FROM TableB L
                                          right OUTER JOIN TableA A
                                          ON l.field1 = a.field1
                                          left OUTER JOIN TableB R
                                          ON a.field2 = r.field2
                                          )
                                          SELECT aID
                                          ,aField1
                                          ,aField2
                                          ,bID
                                          ,bField1
                                          ,bField2
                                          FROM CTE
                                          WHERE bid IS NOT null

                                          The plan indicates that it should be faster, but that's with dummy data. I'm curious about the performance with real data.

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                                          L Offline
                                          Luc Pattyn
                                          wrote on last edited by
                                          #26

                                          Interesting. IMO it can be simplified further, as the CTE isn't really necessary, so I now have:

                                          SELECT A.ID aID
                                          ,A.Field1 aField1
                                          ,A.Field2 aField2
                                          ,CASE WHEN L.ID IS NULL THEN R.ID ELSE L.ID end bID
                                          ,CASE WHEN L.ID IS NULL THEN R.field1 ELSE L.Field1 END bField1
                                          ,CASE WHEN L.ID IS NULL THEN R.Field2 ELSE L.Field2 END bField2
                                          FROM TableB L
                                          RIGHT OUTER JOIN TableA A ON L.Field1 = A.Field1
                                          LEFT OUTER JOIN TableB R ON A.Field2 = R.Field2
                                          WHERE L.ID IS NOT NULL OR R.ID IS NOT NULL

                                          I have your cases depend on the ID field, not the other fields (where null might be valid) :)

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