Difference between primary key and unique key ?
Answer Posted / alok
There is only two Point:
1. The not null constraint is by default added to primary key, it means, primary key attribute cannot accept null values, whereas, the attribute declared as unique can accept null values. It is the major difference between the two.
2. Secondly, we can have only one primary key in a relation, whereas, multiple attributes can be declared unique at the same time.
Is This Answer Correct ? | 0 Yes | 0 No |
Post New Answer View All Answers
How to grant create session privilege to a user in oracle?
What is meant by joins?
 What are the oracle DML commands possible through an update strategy?
Can you drop an index associated with a unique or primary key constraint?
What are the restrictions in a oracle read only transaction?
How can we create the complete backup of data in the oracle.
What is object data modeling?
What are the oracle differences between nvl and coalesce
Please send me Informatica 8.1 certification dumps, my mail id mona85gupta@gmail.com
Why do you create or replace procedures rather that drop and recreate.
How many file formats are supported to export data?
In Oracle Clinical 4.5.0, can the VIEW_TEMPLATE_ID column in DATA_EXTRACT_VIEWS table contain NULL value?
Explain a synonym?
Explain integrity constraint?
What is tns entry?