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Pt1420 Unit 2 Assignment 2

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ASSIGNMENT 02 Key: A key is an attribute or set of attribute in a relation that identifies a tuple in a relation. Followings are the keys used in Data Base Management System. 1) Super Key: A set of attributes of relations for which it holds in all relation there are no two rows that have same values for attributes. 2) Primary Key: A primary key is a value that can be used to identify the unique row in table. For Example: .) Social Security Number .) NIC number 3) Compound Key: A compound key that consists of two or more attribute .
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