Let R1(a, b, c) and R2(x, y, z) be two relations in which a is the foreign key of R1 that refers to the primary key of R2. Consider the following four options.
Which of the following is/are correct about the referential integrity constraint?
1
Insert into R1 will cause violation.
2
Insert into R2 will cause violation.
3
Delete from R1 will cause violation.
4
Delete from R2 will cause violation.