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Relational Algebra is a set of basic operations used to influence the data in relational model. These operations allow the user to specify basic retrieval request. The result of retrieval is a new relation, produced from one or more relations. These operations can be divided in two categories:
• Basic Set Operations
1) UNION
2) SET DIFFERENCE
3) INTERSECTION
4) CARTESIAN PRODUCT
• Relational Operations
1) JOIN
2) PROJECT
3) SELECT
4) DIVISION
why are older data models are being replaced by new data models
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