# Relational Schema

 Question 1
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 be used to refer to tuples of R.

Which one of the following choices is correct?
 A Both S1 and S2 are true B S1 is true and S2 is false C S1 is false and S2 is true D Both S1 and S2 are false
GATE CSE 2021 SET-2   Database Management System
Question 1 Explanation:
 Question 2
Consider the relation $R(P,Q,S,T,X,Y,Z,W)$ with the following functional dependencies.

$PQ\rightarrow X;\quad P\rightarrow YX;\quad Q\rightarrow Y; \quad Y\rightarrow ZW$

Consider the decomposition of the relation R into the constituent relations according to the following two decomposition schemes.

$D1:\quad R=[(P,QS,T);\;(P,T,X);\;(Q,Y);\;(Y,Z,W)]$
$D2:\quad R=[(P,Q,S);\;(T,X);\;(Q,Y);\;(Y,Z,W)]$

Which one of the following options is correct?
 A D1 is a lossless decomposition, but D2 is a lossy decomposition. B D1 is a lossy decomposition, but D2 is a lossless decomposition. C Both D1 and D2 are lossless decompositions. D Both D1 and D2 are lossy decompositions.
GATE CSE 2021 SET-1   Database Management System
Question 2 Explanation:
 Question 3
Immunity of the external schemas (or application programs) to changes in the conceptual scheme is referred to as:
 A Physical Data Independence B Logical Data Independence C Both (A) and (B) D None of the above
ISRO CSE 2018   Database Management System
Question 3 Explanation:
 Question 4
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?
 A {Last Name} B {Room} C {Shift} D {Room, Shift}
ISRO CSE 2018   Database Management System
Question 4 Explanation:
 Question 5
What does a data dictionary will identify?
 A Field name B Field format C Field types D All of the above
ISRO CSE 2017   Database Management System
Question 5 Explanation:
 Question 6
Goals for the design of the logical scheme include
 A avoiding data inconsistency B being able to construct query easily C being able to access data efficiently D All of the above
ISRO CSE 2016   Database Management System
Question 6 Explanation:
 Question 7
Which of the following is NOT a superkey in a relational schema with attributes V,W, X, Y, Z and primary key V Y?
 A VXYZ B VWXZ C VWXY D VWXYZ
GATE CSE 2016 SET-1   Database Management System
Question 7 Explanation:
 Question 8
If $D_1,D_2,...D_n$ are domains in a relational model, then the relation is a table, which is a subset of
 A $D_{1} \oplus D_{2} \oplus \cdots \oplus D_{n}$ B $D_{1} \times D_{2} \times \cdots \times D_{n}$ C $D_{1} \cup D_{2} \cup \cdots \cup D_{n}$ D $D_{1} \cap D_{2} \cap \cdots \cap D_{n}$
ISRO CSE 2015   Database Management System
Question 8 Explanation:
 Question 9
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?
 A CD B EC C AE D AC
ISRO CSE 2015   Database Management System
Question 9 Explanation:
 Question 10
The maximum length of an attribute of type text is
 A 127 B 255 C 256 D It is variable
ISRO CSE 2015   Database Management System
Question 10 Explanation:
There are 10 questions to complete.

### 4 thoughts on “Relational Schema”

1. Options are wrong in question no 18