Question discussion

Which of the following statements about a foreign key is correct?

1969Medium DSSSB TGT Computer Science 0 replies 1 views

AIt can contain duplicate values and, unless declared NOT NULL, NULL values in the referencing table
BIt must always be unique in the referencing table
CIt can never be NULL
DIt must be the primary key of the referencing table

Correct answer: A

Explanation

Many rows may refer to the same parent row, and a foreign key column may be NULL when the relationship is optional.

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