Question

Let for any relation R. I_R represents operation insert into R and D_R represents operation delete from R. Assume that a relation R2 has a foreign key that refers to primary key of another relation R1. Two operations that may cause violation of referential integrity constraints are:
1. I_R1 and I_R2
2. D_R1 and D_R2
3. I_R1 and D_R2
4. I_R2 and D_R1

Answer 1

Correct Answer - Option 4 : I_R2 and D_R1

Table R1(Having Primary Key)
A	B	C
1
2
3

 

Table R2(Having Foreign Key)
A	B	C
1
2
3

 

 

 

 

 

 

• Insert into R1 cannot cause any violation.
• Insert into R2 can cause violation if any value is inserted into D of R2 which value is not in A in R1
• Delete from R1 can cause violation if any tuple is deleted which is referenced to by D in R2.
• Delete from R2 cannot cause any violation

Violation of referential integrity constraints are: D_R1 and IR2

Option 4 is correct.