Database-Management-System
August 29, 2024Database-Management-System
August 29, 2024Database-Management-System
| Question 509 |
There exists a construct which returns a value ‘true’ if the argument subquery is :
| empty | |
| non-empty | |
| in error | |
| none of the above |
Question 509 Explanation:
The exists construct returns the value true if the argument subquery is nonempty.
1. exists r ⇔ r ≠ ∅
2. not exists r ⇔ r = ∅
1. exists r ⇔ r ≠ ∅
2. not exists r ⇔ r = ∅
Correct Answer: B
Question 509 Explanation:
The exists construct returns the value true if the argument subquery is nonempty.
1. exists r ⇔ r ≠ ∅
2. not exists r ⇔ r = ∅
1. exists r ⇔ r ≠ ∅
2. not exists r ⇔ r = ∅