Multiple choice

The following table has two attributes A and C where A is the primary key and C is the foreign key referencing A with on-delete cascade.

The set of all tuples that must be additionally deleted to preserve referential integrity when the tuple (2,4) is deleted is:

  1. (3,4) and (6,4)

  2. (5,2) and (7,2)

  3. (5,2)(7,2) and (9,5)

  4. 1

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

On delete cascade says that deletion of a primary key value should delete its all foreign key references. So in (2,4) 2 is primary key so tuples (5,2) & (7,2) should be deleted, but in (5,2) 5 is also a key so (9,5) also deleted cascade.