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Thread: unique key

  1. #1
    Join Date
    Feb 2004
    Posts
    19

    Unanswered: unique key

    hi ,
    is there any unique key command in plsql.
    what is the diff between primary key and unique key.
    can an unique key be null.

    thanks
    kiran

  2. #2
    Join Date
    Sep 2003
    Location
    The extremely Royal borough of Kensington, London
    Posts
    778
    1) field VARCHAR2(10) UNIQUE
    2) No column that is part of the primary key can contain a null value
    3) A column defined with UNIQUE can contain null values.
    Last edited by r123456; 02-11-04 at 01:30.
    Bessie Braddock: Winston, you are drunk!
    Churchill: And Madam, you are ugly. And tomorrow, I'll be sober, and you will still be ugly.

  3. #3
    Join Date
    Oct 2003
    Posts
    87

    Re: unique key

    Originally posted by madala99
    hi ,
    is there any unique key command in plsql.
    what is the diff between primary key and unique key.
    can an unique key be null.

    thanks
    kiran
    PL/SQL can execute any DDL statement. A PK is the candidate key chosen as the PK, and should consist of the columns most used when accessing the table. Other candidate keys become Alternate Keys (AKs). Both are unique.
    Oracle - DB2 - MS Access -

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