Question 16776 – Data-Structures
December 19, 2023Database-Management-System
December 19, 2023Database-Management-System
| Question 13 |
Consider the following statements S1 and S2 about the relational data model:
S1: A relation scheme can have at most one foreign key.
S2: A foreign key in a relation schema R cannot be used to refer to tuples of R.
Which one of the following choices is correct?
S1: A relation scheme can have at most one foreign key.
S2: A foreign key in a relation schema R cannot be used to refer to tuples of R.
Which one of the following choices is correct?
| S1 is false and S2 is true. | |
| Both S1 and S2 are false. | |
| Both S1 and S2 are true.
| |
| S1 is true and S2 is false. |
Question 13 Explanation:
- A database table may have more than one foreign key, and each foreign key can have a different parent table. Hence, the statement I is incorrect.
- A foreign key is a set of attributes in a table that refers to the primary key of another table or to the primary key of the same table (self-referential table). Hence, the statement II is also incorrect.
Correct Answer: B
Question 13 Explanation:
- A database table may have more than one foreign key, and each foreign key can have a different parent table. Hence, the statement I is incorrect.
- A foreign key is a set of attributes in a table that refers to the primary key of another table or to the primary key of the same table (self-referential table). Hence, the statement II is also incorrect.