Question

Given the following relation schemas, instances, primary and foreign key constraints, list all constraint violations.

R(A,D)
S(A,B,C)
S.A is a foreign key to R.A.
C and D have string domains.  A and B have integer domains.

R(A,D)
A	D
1	aa
2	null
null	4
5	b3c
X	4

S(A,B,C)
A	B	C
1	aa	X
4	4	null
3	null	Y
null	3	Z
1	2	Z

Answer 1

1)

PRIMARY KEY - A combination of a NOT NULL and UNIQUE. Uniquely identifies each row in a table

NOT NULL - Ensures that a column cannot have a NULL value

Above table violates Primary key constraint where A is the primary key of R. And R.A has a null value which violates the primary key constrain. Also, it violates NOT NULL Constraint.

2. Domain Constraint

Table S, R violates domain constraint. In the description, it is given that C and D have string domains, A and B have integer domains. But in R.A we have X which is not an integer, R.D has integers which is not a string, S.B has "aa" which is not an integer.