Computer Science, asked by kamalrakholiya397, 10 months ago

Why foreign key are allowed to have NULL values? Explain with an example.

Answers

Answered by Anonymous

5

Explanation:

When a UNIQUE constraint is defined on the foreign key, only one row in the child table can reference a given parent key value. This model allows nulls in the foreign key. This model establishes a one-to-one relationship between the parent and foreign keys that allows undetermined values (nulls) in the foreign key.

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