Database-Management-System
August 29, 2024Database-Management-System
August 29, 2024Database-Management-System
| Question 319 |
If E1 and E2 are relational algebra expressions then which of the following is NOT a relational
algebra expression
algebra expression
| E1 U E2 | |
| El X E2 | |
| E1 – E2 | |
| E1 / E2 |
Question 319 Explanation:
Six basic operators in relational algebra:
Select σ selects a subset of tuples from reln
Project π deleted unwanted columns from reln
Cartesian Product × allows to combine two relations
Set-difference – tuples in reln. 1, but not in reln. 2
Union ∪ tuples in reln 1 plus tuples in reln 2
Rename ρ renames attribute(s) and relation
Select σ selects a subset of tuples from reln
Project π deleted unwanted columns from reln
Cartesian Product × allows to combine two relations
Set-difference – tuples in reln. 1, but not in reln. 2
Union ∪ tuples in reln 1 plus tuples in reln 2
Rename ρ renames attribute(s) and relation
Correct Answer: D
Question 319 Explanation:
Six basic operators in relational algebra:
Select σ selects a subset of tuples from reln
Project π deleted unwanted columns from reln
Cartesian Product × allows to combine two relations
Set-difference – tuples in reln. 1, but not in reln. 2
Union ∪ tuples in reln 1 plus tuples in reln 2
Rename ρ renames attribute(s) and relation
Select σ selects a subset of tuples from reln
Project π deleted unwanted columns from reln
Cartesian Product × allows to combine two relations
Set-difference – tuples in reln. 1, but not in reln. 2
Union ∪ tuples in reln 1 plus tuples in reln 2
Rename ρ renames attribute(s) and relation