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  1. #1
    Join Date
    Oct 2004
    Posts
    54

    Unanswered: SQL Select stmt using multiple tables

    i have a very simple question,
    when using the select stmts, i usually just use
    2 tables.

    ex.
    select author.id, book.id
    from author, book
    where author.id = book.authorid;

    can you guys give me a very basic select stmts
    using three, four, five, etc tables.....
    let us assume that only AND will be used and
    only table values compared with another table
    values will be used... (ex. this will not be used: author.id = 111)

    my idea is somthing like is, i'm not sure if this is correct

    3 tables
    select author.id, book.id, library.id
    from author, book, library
    where author.id = book.authorid AND author.id = library.auhorid;

    *** i will use the primary key of the 1st table to join to the 3rd table.

    4 tables
    select author.id, book.id, library.id, librarian.name
    from author, book, library
    where author.id = book.authorid AND library.id = librarian.libraryid;

    *** 1st table is join to 2nd table and 3rd table is joined to 4th table.

    5 tables
    I HVE NO IDEA...

    PLEASE HELP ME!!!!!!!!!!!!

  2. #2
    Join Date
    Jan 2004
    Posts
    492
    Wellll....

    Yea you have the idea on multiple joins - you just use AND and the next join. But for us to answer the question (and I dont really see one here) we would have to understand how your database is set up.

    Joins are joins - for every extra table you add, it should have a join to one of the other tables, or you need to go back to the drawing board and start normalizing some more!

    I mean if you just an example here goes - it wont mean anything but..
    Code:
    select a.col1, b.col1, c.col1. d.col1
    from a,b,c,d
    where a.id = b.id and
             a.id = c.id and
             d.col2 = c.col2
    Since I havent used the emp/dept tables in ages, I can't think of a good example using more than 2 of those tables.
    Last edited by ss659; 12-13-04 at 23:13.
    Oracle OCPI (Certified Practicing Idiot)

  3. #3
    Join Date
    Oct 2004
    Posts
    54
    ok, thanks for the help.

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