Relational Algebra

• It is procedural query language.

• It gives a step by step process to obtain the result of the query.

• It uses operators to perform queries.

Types of Relational Operation

1. Select Operation

• Selects the tuples that satisfies a given predicate.

• Denoted by sigma (σ).

2. Project Operation

• Shows the list of those attributes that we wish to appear in the result.

• Denoted by ∏.

3. Union Operation

• Union operation contains all the tuples that are either in table A or B or both A and B.

• Notation: A∪B

4. Set Intersection:

• Suppose there are two tuples R and S. The set intersection operation contains all tuples that are in both R & S.
• Notation: R ∩ S

5. Set Difference:

• Suppose there are two tuples R and S. The set intersection operation contains all tuples that are in R but not in S.
• Notation: R - S

6. Cartesian Product:

• The Cartesian product is used to combine each row in one table with each row in the other table.
• Notation: R x S

7. Rename Operation:

• Rename the output relation.
• Denoted by rho(ρ)