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what is difference between foreign key and reference key
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Hi, i give the definitions with easy understand exapmles
A primary key is used to uniquely identify each row in a
table. It can either be part of the actual record itself,
or it can be an artificial field (one that has nothing to
do with the actual record).
A primary key can consist of one or more fields on a table.
When multiple fields are used as a primary key, they are
called a composite key.
EX:If we take EMP table, Empno is the primary key and in
DEPT table, Deptno is the primary keys
A foreign key is a field (or fields) that points to the
primary key of another table.
The purpose of the foreign key is to ensure referential
integrity of the data.
In other words, only values that are supposed to appear in
the database are permitted
EX:In EMP table Deptno field is the foreign key because it
pointing to the Deptno in DEPT table
A Reference key is a field (or fields) that points to the
primary key of the same table
EX:In EMP table Mgr field is the Reference key because it
pointing to the Empno field in the same table
| Is This Answer Correct ? | 64 Yes | 12 No |
Answer / soujanya
Foreign key is the key i.e. attribute which refers to
another table primary key. Reference key is the primary key
of table referred by another table.
| Is This Answer Correct ? | 37 Yes | 16 No |
Answer / anup
very simple...we use primary key or foreign key whenever we need to make relation.ex..if we need to join student (Roll P.K) and marks(roll F.K.) then we can join both tables only if we have primary key in one table and foreign key in other..one table may have n numbers of foreign key and n number of primary key (Called composite key)..mail me if u need more details in oracle or any front end lang...anup from chennai,Ranchi.
| Is This Answer Correct ? | 8 Yes | 27 No |
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