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**Relational Algebra**

Relational Algebra is a set of basic operations used to manipulate the data in relational model. These operations can be classified in two categories:

1. Basic Set Operations

- Union
- Intersection
- Set Difference
- Cartesian Product

2. Relational Operations

- Select
- Project
- Join
- Division

### Union

If R1 and R2 are two union compatible relations then R3 = R1 ∪ R2 is the relation containing tuples that are either in R1 or in R2 or in both.

### Intersection

If R1 and R2 are two union compatible relations, then the result of R3 = R1 ∩R2 is the relation that includes all tuples that are in both the relations

### Set Difference

If R1 and R2 are two union compatible relations then result of R3 =R1– R2 is the relation that includes only those tuples that are in R1 but not in R2.

### Cartesian Product

If R1 and R2 are two functions or relations, then the result of R3 = R1 × R2 is the combination of tuples that are in R1 and R2.

Degree (R3) =Degree of (R1) + Degree (R2).