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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
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- (3, 4) and (6, 4)
- (5, 2) and (7, 2)
- (5, 2), (7, 2) and (9, 5)
- (3, 4), (4, 3) and (6, 4)
- (3, 4) and (6, 4)
Correct Option: C
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.
Hence (c) is correct option.
