Foreign Key

Consider the following statements S1 and S2 about the relational data model: S1: A relation scheme can have at most one foreign key. S2: A foreign key in a relation scheme R cannot...

Consider the relations $$r(A, B)$$ and $$s(B, C),$$ where $$s.B$$ is a primary key and $$r.B$$ is a foreign key referencing $$s.B.$$ Consider the query $$Q:$$ $$\,\,\,\,\,\,\,\,\,$...

Consider the following tables T1 and T2. In table T1, P is the primary key and Q is the foreign key referencing R in table T2 with on-delete cascade and on-update cascade. In table...

Given the following statements: S1: A foreign key declaration can always be replaced by an equivalent check assertion in SQL. S2: Given the table R(a,b,c) where a and b together fo...

Suppose R 1 ( A, B) and R 2 ( C, D) are two relation schemas. Let r 1 and r 2 be the corresponding relation instances. B is a foreign key that refers to C in R 2 . If data in r 1 a...

Let R 1 ( A, B, C) and R 2 ( D, E) be two relation schema, where the primary keys are shown underlined, and let C be a foreign key in R 1 referring to R 2 . Suppose there is no vio...

Consider two tables in a relational database with columns and rows as follows: Table: Student Roll_no Name Dept_id 1 ABC 1 2 DEF 1 3 GHI 2 4 JKL 3 Table: Department Dept_id Dept_na...

Let $$R (a, b, c)$$ and $$S(d, e, f)$$ be two relations in which $$d$$ is the foreign key of $$S$$ that refers to the primary key of $$R.$$ Consider the following four operations $...