Interested to Buy Any Domain ? << Click Here >> for more details...
what is the use of composite key constraint?
- 2 Answers
- 8442 Views
- I also Faced
- E-Mail Answers
Answers were Sorted based on User's Feedback
Answer / deva
its used to create a primary keys based on two or more
columns in the particular table.
By the set, those should be unique.
| Is This Answer Correct ? | 14 Yes | 3 No |
Answer / srikanth
A composite key is used to club primary key for more than
once column.
PRIMARY KEY(<<COLUMN1>>,<<COLUMN2>>....<<COLUMNN>>)
But the disadvantage is that it will allow duplicates for
any one of the fields.
Example:
CREATE TABLE Example1
(Id INT NOT NULL,Pername VARCHAR(20) NULL,Phno INT NOT NULL
PRIMARY KEY(Id,Phno)
)
Command(s) completed successfully.
INSERT INTO Example1
VALUES(1,'sri',1111)
(1 row(s) affected)
INSERT INTO Example1
VALUES(1,'sri',6666)
(1 row(s) affected)
SELECT * FROM Example1
Id Pername Phno
1 sri 1111
1 sri 6666
As you can see that it is allowing same Id.
Basically Composite Key will take all the fields defined as
a group.So it is least bothered about any one of the field.
| Is This Answer Correct ? | 8 Yes | 0 No |
What are the various types of snapshots ?
What are the components of Physical database structure of Oracle Database?
what are the disadvantages of hierarchial database over RDBMS?
what is difference between table and view? where to use views? thanks in advance!
How do I limit the number of rows returned by an oracle query after ordering?
Explain an index?
What is an Extent ?
What is the difference between RBBMS & DBMS?
how to handle exceptions in post production
What is a nvl function? How can it be used?
Can we call a trigger inside a function and function inside a trigger? Give example.
How to load data from external tables to regular tables?
Oracle General 
