Top 40 DBMS & SQL Placement Questions and Answers

Updated: Jun 15

A Database Management System (DBMS) enables a company to routinely produce, update, archive, and retrieve a collection of data at a faster rate. Apart from software engineer profiles, DBMS is essential for various data analyst profiles in companies such as impend Analytics, Fractal, latent view analytics etc.

Following is the top DBMS & SQL Placement MCQ questions and answers to help you crack best company placements.



Basic DBMS & SQL Placement Questions


Q1. The domain of an attribute in a relation is

  • The Relationship between the attributes

  • set of values that can uniquely identify each tuple of a relation

  • The set of all permitted values of that attribute

  • Property of an entity set

Correct Answer: c The set of all permitted values of that attribute

Explanation:

The domain of an attribute is the set of all values permitted for that attribute. It defines the range of values that an attribute in a relation can take. It is used to constrain the values of an attribute to ensure data integrity.


Q2. The logical structure or blueprint of the database is called

  • Index

  • Relational model

  • Database Schema

  • Database diagram

Correct Answer: c Database Schema

Explanation:

The database schema explains the construction and structure of the database. It contains the information about the tables, indexes, views, etc., in a database. So, the correct answer is Database Schema


Q3. The COLLATE operator in SQL is used to

  • change the data type of an attribute

  • sort the data in the table according to the specified collation

  • combine all the data in a table and store it in a file

  • sort the tuples in a relation in alphabetical order

Correct Answer: b sort the data in the table according to the specified collation

Explanation:

The set of rules used to compare the characters or strings in a database is called collation. The COLLATE clause in SQL is used to sort the strings according to the specified collation.


Q4. An enum field can take how many different values at the maximum?

  • 1024

  • 65536

  • 255

  • 65535

Correct Answer: d 65535


Q5. Which of the following is an example of derived attribute?

  • Name

  • Emp Id

  • Date of Joining

  • Experience

Correct Answer: d Experience

Explanation:

An attribute which is derived from another attribute is called a derived attribute. In the given ER diagram, the ‘Experience’ attribute can be derived from the ‘Date of Joining’ attribute. Hence, ‘experience’ is the derived attribute.


Q6. Which SQL statement is used to remove all the tuples from a relation?

  • DROP

  • REMOVE

  • TRUNCATE

  • All the above

Correct Answer: c TRUNCATE

Explanation:

DROP statement deletes the entire table irrevocably. TRUNCATE is a DDL statement that is used to delete all the tuples in the table, preserving the structure of the table.


Q7. Which of the following statements can be used to get a name which starts with ‘D’ and ends with ‘i’ using LIKE clause in SQL?

  • LIKE ‘d%i’

  • LIKE ‘&d%i’

  • LIKE ‘_d_i’

  • LIKE ‘^d_i&’

Correct Answer: a LIKE ‘d%i’

Explanation: The SQL LIKE operator is used to search for a specific pattern in a string.

% represents one or more characters.

_ represents a single character.

So, the correct answer is LIKE ‘d%i’. Because, it represents the pattern which starts with ‘d’, has one or more characters in between and ends with ‘i’.


Q8. A relation is in 3NF if

  • Every non-prime attribute is functionally dependent on the primary key

  • Every prime attribute is functionally dependent on a non-prime attribute

  • Some non-prime attributes are functionally dependent on the primary key

  • If all the functional dependencies have a super key on their right side

Correct Answer: a Every non-prime attribute is functionally depend to the primary key

Explanation:

The third normal form removes transitive dependency from the table. For a relation satisfy 3NF, either LHS should be a super key or RHS should be prime attribute in every FD of the relation.


Q9. The data which provides data about the database is called

  • Index

  • Metadata

  • Schema

  • File

Correct Answer: b metadata

Explanation:

Metadata contains the information about the data organization, files, tables etc., in the database. Data about the database is called Metadata. Hence, the correct answer is ‘metadata’.


Q10. Two attributes are functionally dependent if and only if

  • Together they constitute a composite key

  • The relation is in third normal form

  • Together they constitute a foreign key.

  • Value in one column determines the value of the other column


Correct Answer: a together they constitute a composite key

Explanation:

Certain functional dependencies can be proved to hold on the schema using the given set of functional dependencies. Hence, two attributes that are functionally dependent, form a composite key for the relation.




For more DBMS & SQL placement questions and answers download our free handbook below.

 

Mobiprep handbooks are free downloadable placement preparation resources that can help you ace any company placement process. We have curated a list of the 40 most important MCQ questions with detailed explanations to ensure the best placement preparation.

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