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Which of the following is not a unary operation?
Which of the following is not a unary operation?
1). select
2). project
3). union
4). rename
1). select
2). project
3). union
4). rename
This Question has 3 answers.
The select, project, and rename operations are called unary operations, because they operate on one relation. The other three operations i.e. union, set difference, Cartesian product operate on pairs of relations and are, therefore, called binary operations.
Union
The union operation is not a unary operation.
Explanation: Unary operations operate on a single relation. Binary operations require two relations.
Explanation: Unary operations operate on a single relation. Binary operations require two relations.
Unary Operations:
- Select (σ) → Filters rows from a relation.
- Project (π) → Selects specific columns from a relation.
- Rename (ρ) → Renames a relation or its attributes.
- Union (∪) → Combines two relations with the same schema.
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