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GeekInterview.com > Interview Questions > Oracle > SQL Plus
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Question: What is the basic difference between primary key and (unique key along with Not NULL).
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| September 09, 2007 14:40:33 |
#6 |
| glakshkar |
Member Since: September 2007 Total Comments: 3 |
RE: What is the basic difference between primary key a...
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Hi Anil,
Apart from NOTNULL, I can tell you one more difference.
We can define Primary key on only one column in a table.
But for Unique key there is no limit. we can define as many columns as we want.
THis is totally wrong Primary key too can contain multiple column.
Dear Anil,
we can achieve PK functionality via using Unique key+ Not Null contsraint
but it's not gud practice, when u can achieve same functionality via single PK constraint
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