
Information about Primary key and Foreign key - Essie654
http://www.programmingeeks.com/difference-primary-key-foreign-key/
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Essie654
SQL server has seven types of keys. primary key and foreign key are important
keys to them. Each table has only one primary key in a database table. Because
of its unique, not accept the null value and duplicate value. We can create
more than one foreign key in tables.

