McqMate
Chapters
1. |
Relational Algebra is a __________ query language that takes two relations as input and produces another relation as an output of the query. |
A. | Relational |
B. | Structural |
C. | Procedural |
D. | Fundamental |
Answer» C. Procedural |
2. |
For select operation the ________ appear in the subscript and the ___________ argument appears in the paranthesis after the sigmA:) |
A. | Predicates, relation |
B. | Relation, Predicates |
C. | Operation, Predicates |
D. | Relation, Operation |
Answer» A. Predicates, relation |
3. |
The ___________ operation, denoted by −, allows us to find tuples that are in one relation but are not in another. |
A. | Union |
B. | Set-difference |
C. | Difference |
D. | Intersection |
Answer» B. Set-difference |
4. |
In precedence of set operators, the expression is evaluated from |
A. | Left to left |
B. | Left to right |
C. | Right to left |
D. | From user specification |
Answer» B. Left to right |
5. |
Which one of the following is a set of one or more attributes taken collectively to uniquely identify a record? |
A. | Candidate key |
B. | Sub key |
C. | Super key |
D. | Foreign key |
Answer» C. Super key |
6. |
Consider attributes ID, CITY and NAME. Which one of this can be considered as a super key? |
A. | NAME |
B. | ID |
C. | CITY |
D. | CITY, ID |
Answer» B. ID |
7. |
A _____ is a property of the entire relation, rather than of the individual tuples in which each tuple is unique. |
A. | Rows |
B. | Key |
C. | Attribute |
D. | Fields |
Answer» B. Key |
8. |
An attribute in a relation is a foreign key if the _______ key from one relation is used as an attribute in that relation. |
A. | Candidate |
B. | Primary |
C. | Super |
D. | Sub |
Answer» B. Primary |
9. |
The relation with the attribute which is the primary key is referenced in another relation. The relation which has the attribute as a primary key is called ______________ |
A. | Referential relation |
B. | Referencing relation |
C. | Referenced relation |
D. | Referred relation |
Answer» C. Referenced relation |
10. |
The ______ is the one in which the primary key of one relation is used as a normal attribute in another relation. |
A. | Referential relation |
B. | Referencing relation |
C. | Referenced relation |
D. | Referred relation |
Answer» C. Referenced relation |
11. |
A _________ integrity constraint requires that the values appearing in specified attributes
|
A. | Referential |
B. | Referencing |
C. | Specific |
D. | Primary |
Answer» A. Referential |
12. |
A relational database consists of a collection of |
A. | Tables |
B. | Fields |
C. | Records |
D. | Keys |
Answer» A. Tables |
13. |
A ________ in a table represents a relationship among a set of values. |
A. | Column |
B. | Key |
C. | Row |
D. | Entry |
Answer» C. Row |
14. |
The term _______ is used to refer to a row. |
A. | Attribute |
B. | Tuple |
C. | Field |
D. | Instance |
Answer» B. Tuple |
15. |
The term attribute refers to a ___________ of a table. |
A. | Record |
B. | Column |
C. | Tuple |
D. | Key |
Answer» B. Column |
16. |
For each attribute of a relation, there is a set of permitted values, called the ________ of that attribute. |
A. | Domain |
B. | Relation |
C. | Set |
D. | Schema |
Answer» A. Domain |
17. |
Database __________ which is the logical design of the database, and the database _______ which is a snapshot of the data in the database at a given instant in time. |
A. | Instance, Schema |
B. | Relation, Schema |
C. | Relation, Domain |
D. | Schema, Instance |
Answer» D. Schema, Instance |
18. |
Course(course_id,sec_id,semester) Here the course_id,sec_id and semester are __________ and course is a _________ |
A. | Relations, Attribute |
B. | Attributes, Relation |
C. | Tuple, Relation |
D. | Tuple, Attributes |
Answer» B. Attributes, Relation |
19. |
Department (dept name, building, budget) and Employee (employee_id, name, dept name, salary) Here the dept_name attribute appears in both the relations. Here using common attributes in relation schema is one way of relating ___________ relations. |
A. | Attributes of common |
B. | Tuple of common |
C. | Tuple of distinct |
D. | Attributes of distinct |
Answer» C. Tuple of distinct |
20. |
A domain is atomic if elements of the domain are considered to be ____________ units. |
A. | Different |
B. | Indivisbile |
C. | Constant |
D. | Divisible |
Answer» B. Indivisbile |
21. |
The tuples of the relations can be of ________ order. |
A. | Any |
B. | Same |
C. | Sorted |
D. | Constant |
Answer» A. Any |
22. |
Choose the correct statement regarding superkeys |
A. | A superkey is an attribute or a group of multiple attributes that can uniquely identify a tuple |
B. | A superkey is a tuple or a set of multiple tuples that can uniquely identify an attribute |
C. | Every superkey is a candidate key |
D. | A superkey is an attribute or a set of attributes that distinguish the relation from other relations |
Answer» A. A superkey is an attribute or a group of multiple attributes that can uniquely identify a tuple |
23. |
What is an Instance of a Database? |
A. | The logical design of the database system |
B. | The entire set of attributes of the Database put together in a single relation |
C. | The state of the database system at any given point of time |
D. | The initial values inserted into the Database immediately after its creation |
Answer» C. The state of the database system at any given point of time |
24. |
What is a foreign key? |
A. | A foreign key is a primary key of a relation which is an attribute in another relation |
B. | A foreign key is a superkey of a relation which is an attribute in more than one other relations |
C. | A foreign key is an attribute of a relation that is a primary key of another relation |
D. | A foreign key is the primary key of a relation that does not occur anywhere else in the schema |
Answer» C. A foreign key is an attribute of a relation that is a primary key of another relation |
25. |
What action does ⋈ operator perform in relational algebra |
A. | Output specified attributes from all rows of the input relation and remove duplicate tuples from the output |
B. | Outputs pairs of rows from the two input relations that have the same value on all attributes that have the same name |
C. | Output all pairs of rows from the two input relations (regardless of whether or not they have the same values on common attributes) |
D. | Return rows of the input relation that satisfy the predicate |
Answer» A. Output specified attributes from all rows of the input relation and remove duplicate tuples from the output |
26. |
What does the “x” operator do in relational algebra? |
A. | Output specified attributes from all rows of the input relation. Remove duplicate tuples from the output |
B. | Output pairs of rows from the two input relations that have the same value on all attributes that have the same name |
C. | Output all pairs of rows from the two input relations (regardless of whether or not they have the same values on common attributes) |
D. | Returns the rows of the input relation that satisfy the predicate |
Answer» C. Output all pairs of rows from the two input relations (regardless of whether or not they have the same values on common attributes) |
27. |
An attribute is a __________ in a relation. |
A. | Row |
B. | Column |
C. | Value |
D. | Tuple |
Answer» B. Column |
28. |
What is the method of specifying a primary key in a schema description? |
A. | By writing it in bold letters |
B. | By underlining it using a dashed line |
C. | By writing it in capital letters |
D. | By underlining it using a bold line |
Answer» D. By underlining it using a bold line |
29. |
Statement 1: A tuple is a row in a relation Statement 2: Existence of multiple foreign keys in a same relation is possible |
A. | Both the statements are true |
B. | Statement 1 is correct but Statement 2 is false |
C. | Statement 1 is false but Statement 2 is correct |
D. | Both the statements are false |
Answer» A. Both the statements are true |
30. |
Choose the option that correctly explains in words, the function of the following relational algebra expression σyear≥2009 (book ⋈ borrow) |
A. | Selects all tuples from the Cartesian product of book and borrow |
B. | Selects all the tuples from the natural join of book and borrow wherever the year is lesser than 2009 |
C. | Selects all the tuples from the natural join of book and student wherever the year is greater than or equal to 2009 |
D. | Selects all tuples from the Cartesian product of book and borrow wherever the year is greater than or equal to 2009 |
Answer» B. Selects all the tuples from the natural join of book and borrow wherever the year is lesser than 2009 |
31. |
State true or false: If a relation consists of a foreign key, then it is called a referenced relation of the foreign key dependency. |
A. | True |
B. | False |
C. | none |
D. | all |
Answer» B. False |
32. |
Which of the following information does an SQL DDL not specify? |
A. | The schema for each relation |
B. | The integrity constraints |
C. | The operations on the tuples |
D. | The security and authorization information for each relation |
Answer» C. The operations on the tuples |
33. |
Which of the following data types does the SQL standard not support? |
A. | char(n) |
B. | String(n) |
C. | varchar(n) |
D. | float(n) |
Answer» B. String(n) |
34. |
Which command is used to create a new relation in SQL |
A. | create table( , …) |
B. | create relation( , …) |
C. | new table( , …) |
D. | new relation( , …) |
Answer» A. create table( , …) |
35. |
If a1, a2, a3 are attributes in a relation and S is another relation, which of the following is an incorrect specification of an integrity constraint? |
A. | primary key(a1, a2, a3) |
B. | primary key(a1) |
C. | foreign key(a1, a2) references S |
D. | foreign key(a1, a2) |
Answer» D. foreign key(a1, a2) |
36. |
What is the syntax to load data into the database? (Consider D as the database and a, b, c as datA:) |
A. | enter into D (a, b, C:); |
B. | insert into D values (a, b, C:); |
C. | insert into D (a, b, C:); |
D. | insert (a, b, C:) values into D; |
Answer» B. insert into D values (a, b, C:); |
37. |
Which of the following commands do we use to delete a relation (R) from a database? |
A. | drop table R |
B. | drop relation R |
C. | delete table R |
D. | delete from R |
Answer» A. drop table R |
38. |
Which of the following commands do we use to delete all the tuples from a relation (R)? |
A. | delete table R |
B. | drop table R |
C. | delete from R |
D. | drop from R |
Answer» C. delete from R |
39. |
Choose the correct command to delete an attribute A from a relation R |
A. | alter table R delete A |
B. | alter table R drop A |
C. | alter table drop A from R |
D. | delete A from R |
Answer» B. alter table R drop A |
40. |
create table apartment(ownerID varchar (5), ownername varchar(25), floor numeric(4,0),
|
A. | The statement is syntactically wrong |
B. | It creates a relation with three attributes ownerID, ownername, floor in which floor cannot be null. |
C. | It creates a relation with three attributes ownerID, ownername, floor in which ownerID cannot be null. |
D. | It creates a relation with three attributes ownerID, ownername, floor in which ownername must consist of at least 25 characters. |
Answer» C. It creates a relation with three attributes ownerID, ownername, floor in which ownerID cannot be null. |
41. |
What does the notnull integrity constraint do? |
A. | It ensures that at least one tuple is present in the relation |
B. | It ensures that at least one foreign key is present in the relation |
C. | It ensures that all tuples have a finite value on a specified attribute |
D. | It ensures that all tuples have finite attributes on all the relations |
Answer» C. It ensures that all tuples have a finite value on a specified attribute |
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