Database Management System
Q101.
Consider the relations r1(P, Q, R) and r2(R, S, T) with primary keys P and R respectively. The relation r_{1} contains 2000 tuples and r_{2} contains 2500 tuples. The maximum size of the join r_{1} \Join r_{2} is :Q102.
With regard to the expressive power of the formal relational query languages, which of the following statements is true ?Q103.
Consider the relation Student (\underline{name}, sex, marks), where the primary key is shown underlined, pertaining to students in a class that has at least one boy and one girl. What does the following relational algebra expression produce) (Note: \rho is the rename operator). The condition in join is "(sex=female ^\wedge x=male ^\wedge marks\leq m)"Q104.
Considering the following table in a relational database :\begin{array}{|c|c|c|c|} \hline \text { Last Name } & \text { Rank } & \text { Room } & \text { Shift } \\ \hline \text { Smith } & \text { Manager } & 234 & \text { Morning } \\ \hline \text { Jones } & \text { Custodian } & 33 & \text { Afternoon } \\ \hline \text { Smith } & \text { Custodian } & 33 & \text { Evening } \\ \hline \text { Doe } & \text { Clerical } & 222 & \text { Morning } \\ \hline \end{array}According to the data shown in the table, which of the following could be a candidate key of the table?Q107.
Let R=(A,B,C,D,E,F) be a relation scheme with the following dependencies C \rightarrow F, E \rightarrow A, EC \rightarrow D, A \rightarrow B. Which of the following is a key of R?Q108.
If D_1,D_2,...D_n are domains in a relational model, then the relation is a table, which is a subset ofQ109.
Which of the following is NOT a superkey in a relational schema with attributes V,W, X, Y, Z and primary key V Y?