Purushottam Rathore
What is a candidate key?
By Purushottam Rathore in .NET on May 19 2009
  • PEEYUSH MISHRA
    Jul, 2009 22

    A candidate key is a combination of attributes that can be uniquely used to identify a database record without any extraneous data. Each table may have one or more candidate keys. One of these candidate keys is selected as the table primary key.

    • 0
  • Sanjeev Singh
    May, 2009 26

    A candidate key is one that can identify each row of a
    table uniquely. Generally a candidate key becomes the
    primary key of the table. If the table has more than one
    candidate key, one of them will become the primary key, and
    the rest are called alternate keys.

    A key formed by combining at least two or more columns is
    called composite key.

    • 0
  • Purushottam Rathore
    May, 2009 19

    A table may have more than one combination of columns that could uniquely identify the rows in a table; each combination is a candidate key. During database design you can pick up one of the candidate keys to be the primary key. For example, in the supplier table supplierid and suppliername can be candidate key but you will only pick up supplierid as the primary key.

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