Database-Management-System
January 9, 2024Question 7538 – HCU PHD CS MAY 2017
January 9, 2024Database-Management-System
| Question 674 |
Integrity constraints ensure that changes made to the database by authorized users do not result into loss of data consistency. Which of the following statement(s) is (are) true w.r.t. the examples of integrity constraints ?
(A) An instructor Id. No. cannot be null, provided Instructor Id No. being primary key.
(B) No two citizens have same Adhar-Id.
(C) Budget of a company must be zero.
(A) An instructor Id. No. cannot be null, provided Instructor Id No. being primary key.
(B) No two citizens have same Adhar-Id.
(C) Budget of a company must be zero.
| (A), (B) and (C) are true. | |
| (A) false, (B) and (C) are true. | |
| (A) and (B) are true; (C) false. | |
| (A), (B) and (C) are false |
Question 674 Explanation:
Primary key, every table have at least one attribute as “primary key”. No primary key should ever have null values.
Statement-1: TRUE: Here, instructor ID is primary key. So, they mentioned it is not null.
Statement-2: TRUE: No two citizens have same Adhar-Id. It is clear example of primary key.
Statement-3: FALSE: Budget of a company must be zero. It is violated constraint of “not null”. Because entity integrity constraints should not accept not null but referential integrity
constraints will accept null value.
Statement-1: TRUE: Here, instructor ID is primary key. So, they mentioned it is not null.
Statement-2: TRUE: No two citizens have same Adhar-Id. It is clear example of primary key.
Statement-3: FALSE: Budget of a company must be zero. It is violated constraint of “not null”. Because entity integrity constraints should not accept not null but referential integrity
constraints will accept null value.
Correct Answer: C
Question 674 Explanation:
Primary key, every table have at least one attribute as “primary key”. No primary key should ever have null values.
Statement-1: TRUE: Here, instructor ID is primary key. So, they mentioned it is not null.
Statement-2: TRUE: No two citizens have same Adhar-Id. It is clear example of primary key.
Statement-3: FALSE: Budget of a company must be zero. It is violated constraint of “not null”. Because entity integrity constraints should not accept not null but referential integrity
constraints will accept null value.
Statement-1: TRUE: Here, instructor ID is primary key. So, they mentioned it is not null.
Statement-2: TRUE: No two citizens have same Adhar-Id. It is clear example of primary key.
Statement-3: FALSE: Budget of a company must be zero. It is violated constraint of “not null”. Because entity integrity constraints should not accept not null but referential integrity
constraints will accept null value.
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