If a 1:M relationship is mandatory on the 1 side and optional on the M side, whi
ID: 3661436 • Letter: I
Question
If a 1:M relationship is mandatory on the 1 side and optional on the M side, which of the following is true?
The resulting foreign key can have null (empty) values
The resulting foreign key cannot have null (empty) values
The resulting foreign key must have null (empty) values
No foreign key is created as a result of mapping such a relationship
The resulting foreign key can have null (empty) values
The resulting foreign key cannot have null (empty) values
The resulting foreign key must have null (empty) values
No foreign key is created as a result of mapping such a relationship
Explanation / Answer
If a 1:M relationship is mandatory on both sides then the resulting foreign key cannot have null values.
For example, if the two tables on both sides have a 1:M relationship then there must be two tables and corresponding attributes. The one end of the foreign key must not be null since the primary attribute of the one end and the corresponding attribute must be foreign key in the other end of the table.
Answer: The resulting foreign key can have null (empty) values