Engineering Questions with Answers - Multiple Choice Questions

MCQs on SQL Basics and SQL Data Definition

1 - Question

Which one of the following is used to define the structure of the relation, deleting relations and relating schemas?
a) DML(Data Manipulation Langauge)
b) DDL(Data Definition Langauge)
c) Query
d) Relational Schema

View Answer

Answer: b
Explanation: Data Definition language is the language which performs all the operation in defining structure of relation.




2 - Question

Which one of the following provides the ability to query information from the database and to insert tuples into, delete tuples from, and modify tuples in the database?
a) DML(Data Manipulation Langauge)
b) DDL(Data Definition Langauge)
c) Query
d) Relational Schema

View Answer

Answer: a
Explanation: DML performs the change in the values of the relation.




3 - Question

CREATE TABLE employee (name VARCHAR, id INTEGER)

What type of statement is this?
a) DML
b) DDL
c) View
d) Integrity constraint

View Answer

Answer: b
Explanation: Data Definition language is the language which performs all the operation in defining structure of relation.




4 - Question

SELECT * FROM employee

What type of statement is this?
a) DML
b) DDL
c) View
d) Integrity constraint

View Answer

Answer: a
Explanation: Select operation just shows the required fields of the relation. So it forms a DML.




5 - Question

The basic data type char(n) is a _____ length character string and varchar(n) is _____ length character.
a) Fixed, equal
b) Equal, variable
c) Fixed, variable
d) Variable, equal

View Answer

Answer: c
Explanation: Varchar changes its length accordingly whereas char has a specific length which has to be filled by either letters or spaces.




6 - Question

An attribute A of datatype varchar(20) has the value “Avi”. The attribute B of datatype char(20) has value ”Reed”. Here attribute A has ____ spaces and attribute B has ____ spaces.
a) 3, 20
b) 20, 4
c) 20, 20
d) 3, 4

View Answer

Answer: a
Explanation: Varchar changes its length accordingly whereas char has a specific length which has to be filled by either letters or spaces.




7 - Question

To remove a relation from an SQL database, we use the ______ command.
a) Delete
b) Purge
c) Remove
d) Drop table

View Answer

Answer: d
Explanation: Drop table deletes the whole structure of the relation .purge removes the table which cannot be obtained again.




8 - Question

DELETE FROM r;   //r - relation

This command performs which of the following action?
a) Remove relation
b) Clear relation entries
c) Delete fields
d) Delete rows

View Answer

Answer: b
Explanation: Delete command removes the entries in the table.




9 - Question

INSERT INTO instructor VALUES (10211, ’Smith’, ’Biology’, 66000);

What type of statement is this?
a) Query
b) DML
c) Relational
d) DDL

View Answer

Answer: b
Explanation: The values are manipulated. So it is a DML.




10 - Question

Updates that violate __________ are disallowed.
a) Integrity constraints
b) Transaction control
c) Authorization
d) DDL constraints

View Answer

Answer: a
Explanation: Integrity constraint has to be maintained in the entries of the relation.

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