Interested to Buy Any Domain ? << Click Here >> for more details...
What is difference between UNIQUE constraint and PRIMARY KEY
constraint ?
- 3 Answers
- 7160 Views
- I also Faced
- E-Mail Answers
Answers were Sorted based on User's Feedback
Answer / allin
The Primarykey Constraint= unique + Not Null constraints.
For the Unique the meaning it self it is telling unique
value. won't accept duplicate values.
Thanks & Regards,
RatnaRao
9833847339
| Is This Answer Correct ? | 9 Yes | 0 No |
Answer / naren
When ever you create a primary key constraint on perticular
column in a table it creates clustered index by default,
it cannot allow null values and a table having only one
primary key constraint. But in the case of Unique Key
constraint, it allow only one null value, it creates non-
clustered index by default and a table having multiple
unique key constraints.
Regards
Naren Krishna
| Is This Answer Correct ? | 8 Yes | 3 No |
Answer / kiran
if unique then it can have null
but if column has primary then it cannot have null values
and duplicate values
| Is This Answer Correct ? | 2 Yes | 1 No |
WHAT IS ecc 6.0
How to start an oracle instance?
What are the common oracle dba tasks?
What is a system tablespace?
What is oracle thin client?
Hi can anyone tell me where are the dumps found of OCA certification.. Also the materials to be studied for the preparation.
What are the ansi data types supported in oracle?
Difference between inner join vs where ?
How to create index-by table in oracle?
Why is oracle so popular?
How does propagation differ between Advanced Replication and Snapshot Replication (read-only)?
Do you know about aggregate functions? What is row num function? Can it be used all databases?
1 Answers Bravura Solutions, Cap Gemini,
Oracle General 
