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Beginners question on LEFT JOINS - MySQL

Yeah, I know this was KINDA covered in databases, but could somebody give me a refresher of what a left join is in, say, terms of tables FOO and BAR. Thanks....

  1. #1

    Default Beginners question on LEFT JOINS



    Yeah, I know this was KINDA covered in databases, but could somebody give me
    a refresher of what a left join is in, say, terms of tables FOO and BAR.
    Thanks.
    John Meyer Guest

  2. #2

    Default Re: Beginners question on LEFT JOINS

    "John Meyer" <john.l.meyer> wrote in message
    news:BbCdnUllJ9IlJjDeRVn-uQcomcast.com...
    > Yeah, I know this was KINDA covered in databases, but could somebody give
    > me
    > a refresher of what a left join is in, say, terms of tables FOO and BAR.
    > Thanks.
    [url]http://www.firstsql.com/tutor3.htm#outer[/url]

    Regards,
    Bill K.


    Bill Karwin Guest

  3. #3

    Default Re: Beginners question on LEFT JOINS

    Bill Karwin wrote:
    >
    > [url]http://www.firstsql.com/tutor3.htm#outer[/url]
    >
    > Regards,
    > Bill K.

    Kind of get that one. It's a little bit harder to get my mind around that
    one. For instance, listing all orders that don't have any items on them,
    would that be an instance where you would use an OUTER/LEFT join.
    John Meyer Guest

  4. #4

    Default Re: Beginners question on LEFT JOINS

    "John Meyer" <john.l.meyer> wrote in message
    news:GKidndMlHPZAUDDenZ2dnUVZ_sWdnZ2dcomcast.com. ..
    > For instance, listing all orders that don't have any items on them,
    > would that be an instance where you would use an OUTER/LEFT join.
    Yes, probably. (it's hard to give a blanket answer because I don't know for
    sure what your database structure is)

    Here's another link that describes outer joins concisely and gives an
    example:
    [url]http://en.wikipedia.org/wiki/Outer_join#Left_outer_join[/url]

    I am reluctant to write a long description of how outer joins work, because
    there are many resources on the internet that explain this already. Do a
    google search for "sql outer join tutorial" or something.

    I sympathize that the typical SQL book doesn't cover this topic well. Try
    reading "SQL for Smarties" by Joe Celko.

    Regards,
    Bill K.


    Bill Karwin Guest

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