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Multiple Primary key in table?

  • July 3, 2013 at 3:55 am

    #296049

    Hi,

    I have doubts multiple primay key on single table,

    Table can be support multiple primary key in this case one Clustred index created by default and other primary key which index name will be created?

    thanks

    ananda

  • July 3, 2013 at 4:18 am

    #1629459

    A table can only have a single clustered index and a single primary key. However these do not have to be the same; you could have a non clustered primary key and a seperate clustered index if that suited your needs.

    In addition, you can have unique indexes; bear in mind that they will allow NULL values whereas a primary key will not.

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  • July 3, 2013 at 4:46 am

    #1629471

    I have tested multiple primary key in single table.

    PK - columname 1 - [id_no]

    PK - columname 2 - [id_nos]

    ALTER TABLE [dbo].[Index_testing] ADD CONSTRAINT [PK_Index_testing] PRIMARY KEY CLUSTERED

    (

    [id_no] ASC,

    [id_nos] ASC

    )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

    GO

    the above statement one clustred index have two Primarykey and two different column name..so it is treated as composite primary key..

  • July 3, 2013 at 4:52 am

    #1629476

    That's not two primary keys. It's one primary key constraint over two columns - a composite key.

    John

  • July 3, 2013 at 4:58 am

    #1629479

    thank you Mr. Johan,

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