If we declare constraints Unique and Not null on a single
column then it will act as a Primary key, so what is the use
of primary key??
- 3 Answers
- 6331 Views
- I also Faced
- E-Mail Answers
Answer Posted / neha sinha
1) Primary key creates clustered index and unique key
creates non-clustered index. Performance wise clustered
index is fast so we need Primary key.
2)if we need more then one primary key in table than we can
use unique key+NOT NULL becous it behave as Primary key but
we cant define more than one column as primary key. :)
| Is This Answer Correct ? | 2 Yes | 1 No |
Post New Answer View All Answers
When is the explicit cursor used ?
What is clause in sql?
What is crud diagram?
How show all rows in sql?
what is the functionality of the function htmlentities? : Sql dba
What is on delete restrict?
How to run sql*plus commands in sql developer?
Is it possible to update views?
State few characteristics of pl/sql?
Can we insert data in view?
What are the types of optimization?
What is the mutating table and constraining table?
What is the use of count (*) in sql?
Write the order of precedence for validation of a column in a table? I. Done using database triggers. Ii. Done using integarity constraints
Write a sql query to find the names of employees that begin with ‘a’?
