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Primary Key and Unique Key

517373Jan 5 2007 — edited Jan 5 2007

Hi All,

I have one query for creating Primary Key & Unique Key.

1) Is there possible to create the primary after loading data.

For example, In EMP table i have inserted 10 rows with duplicates(EMP_ID). After inserting the datas i want to create the primary for EMP_ID. Now EMP_ID duplicate values are enforcing or not?

2) I create one unique constraint for one column. Unique accepts null value. But its not accept duplicate values.

My question is Shall give more than one null value into unique constraint column.

Cheers,

Moorthy.GS

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Locked on Feb 2 2007

Added on Jan 5 2007

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