joining 2 selects where a value not in Values

  • Ok, another question I have 2 queries where I select all accounts with bill code in 'bmonit' example ('12','39','124','1FA')

    then I also have a Select where the same account might have additional services, that are not in example ('12','39','124','1FA') and for these accounts I need to just put a 'Y' if stop_date is null.

  • If I understand your question correctly you need to do what is referred to as a Left Anti Join Semi Join.

    There are a couple ways you can do this:

    DECLARE @bmonit table(billcode varchar(10) not null);

    DECLARE @table2 table(billcode varchar(10) not null, stop_date date null);

    INSERT @bmonit VALUES ('12'),('39'),('124'),('1FA');

    INSERT @table2 VALUES ('12','1/1/2009'),('39','1/1/2009'),('124','1/1/2009'),('1FA','1/1/2009'),('AAA',NULL);

    -- Option 1: Using EXCEPT

    SELECT billcode, 'Y' as xxx FROM @table2

    WHERE stop_date IS NULL

    EXCEPT

    SELECT billcode, 'Y' FROM @bmonit

    -- Option 2: Using NOT IN (this is the better option if you are not filtering out duplicates

    SELECT billcode, 'Y' AS xxx

    FROM @table2 t2

    WHERE stop_date IS NULL

    AND billcode NOT IN

    (

    SELECT billcode FROM @bmonit

    );

    "I cant stress enough the importance of switching from a sequential files mindset to set-based thinking. After you make the switch, you can spend your time tuning and optimizing your queries instead of maintaining lengthy, poor-performing code."

    -- Itzik Ben-Gan 2001

  • Alan.B (8/12/2014)


    If I understand your question correctly you need to do what is referred to as a Left Anti Join Semi Join.

    Not by me! Or anyone else, it seems. Try searching Google for "Left Anti Join Semi Join" and you'll get one hit - yours πŸ˜€

    And very soon, presumably, two hits.

    The absence of evidence is not evidence of absence.
    Martin Rees

    You can lead a horse to water, but a pencil must be lead.
    Stan Laurel

  • Phil Parkin (8/13/2014)


    Alan.B (8/12/2014)


    If I understand your question correctly you need to do what is referred to as a Left Anti Join Semi Join.

    Not by me! Or anyone else, it seems. Try searching Google for "Left Anti Join Semi Join" and you'll get one hit - yours πŸ˜€

    And very soon, presumably, two hits.

    Picky today Phil! πŸ˜›

    It's a typo. Alan meant a left anti semi join.

    β€œWrite the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw

    For fast, accurate and documented assistance in answering your questions, please read this article.
    Understanding and using APPLY, (I) and (II) Paul White
    Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden

  • Aha, OK - perhaps I should have considered that, thanks Chris. Sorry Alan.

    I have reason to be picky - I'm building a WiX installer, so I'm in XML hell πŸ™‚

    The absence of evidence is not evidence of absence.
    Martin Rees

    You can lead a horse to water, but a pencil must be lead.
    Stan Laurel

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