Question

Let relation R2 has a Foreign Key that refers to Primary Key of relation R1. Which of the following operations may cause violation of referential integrity constraints?

I: insert into R1

II: insert into R2

III: delete from R1

IV: delete from R2

1. II and III
2. I and IV
3. I, II and III
4. III and IV

Answer 1

Correct Answer - Option 1 : II and III

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