Organization of data as relations.

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Organization of data as relations

RELATIONS

Entity sets and relationship sets are useful in designing data bases. Entity - relationship sets may be put as a table of values. This is called a Relation. Relation name is entity name. A row of a relation has members of its attributes. The column headings are the names of the attributes.

EXAMPLES OF A RELATION

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RELATION NOTATION

Relation is an entire table

• Vendor relation:

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WHY RELATION ?

Entity set can be easily stored as a flat file in a computer's storage Sound theory of relations allows systematic design of relational data base, reduces duplication of data, tries to eliminate errors in adding, deleting, altering items in a data base and simplifies retrieval of data.

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