What are the difference between primary keys and foreign keys?

Question

Hai,friends anybody say about the difference between primary keys and foreign keys

Answer 1

The primary key is the columns used to uniquely identify each row of a table.It can not accept null,duplicate values. A table can have only one primary key.
Foreign keys are both a method of ensuring data integrity and a manifestation of the relationship between tables. It is a field in database table is primary key in another table. It can accept multiple null,duplicate values.

Answer 2

• Primary key is used to search a record in a database table.
• Foreign key is used to refer primary key of the another table.
  In short, if both the tables are related to each other then it is used.