Which statements are true regarding constraints? Select one or more: A constraint is enforced only for the INSERT operation on a table. A foreign key cannot contain NULL values. A columns with the UNIQUE constraint can contain NULL values. A constraint can be disabled even if the constraint column contains data.
Answer options
A
A foreign key cannot contain NULL values. A columns with the UNIQUE constraint can contain NULL values. A constraint can be disabled even if the constraint column contains dat
B
, A columns with the UNIQUE constraint can contain NULL values.
Correct answer: A foreign key cannot contain NULL values. A columns with the UNIQUE constraint can contain NULL values. A constraint can be disabled even if the constraint column contains dat
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