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rajesh822 Currently Banned New User
Joined: 22 Sep 2005 Posts: 5
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what is diff between primary key and unique index?
Rajesh |
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ikumar
New User
Joined: 02 Aug 2005 Posts: 81
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Primary Key: a relational database constraint. Primary key consists of one or more columns that uniquely identify a row in the table. For a normalized relation, there is one designated primary key.
Unique index: a physical object that stores only unique values. There can be one or more unique indexes on a table. |
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harinatha
New User
Joined: 24 Jul 2005 Posts: 28
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Hi,
Here one more point is added.
Unique key can have one null value(only one), but not in Primary key.
Thanks & Regards,
Hari. |
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khamarutheen
Active Member
Joined: 23 Aug 2005 Posts: 677 Location: NJ
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hi frnd,
the primary key is a key which holds only the unique value and the primary key is set active if the unique index is created where the physical storage is created for the unique values. |
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Kavitha Palani
New User
Joined: 16 Nov 2005 Posts: 8
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Primary Key: a relational database constraint. Primary key consists of one or more columns that uniquely identify a row in the table. For a normalized relation, there is one designated primary key.
Unique index: a physical object that stores only unique values. There can be one or more unique indexes on a table. |
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