What is a Database?
A database is a collection of related data which represents some aspect of the real world. A database system is designed to be built and populated with data for a certain task.
What is DBMS?
Database Management System (DBMS) is a software for storing and retrieving users’ data while considering appropriate security measures. It consists of a group of programs which manipulate the database. The DBMS accepts the request for data from an application and instructs the operating system to provide the specific data. In large systems, a DBMS helps users and other third-party software to store and retrieve data.
DBMS allows users to create their own databases as per their requirement. The term “DBMS” includes the user of the database and other application programs. It provides an interface between the data and the software application.
In this section, we are going to cover some of the basic questions based on DBMS, which are frequently asked during an interview. Here we will try to cover almost all the topics related to DBMS.
1) Relational database is a collection of
C. Record or Row
Explanation: The answer is A. In Relational Database, Field is the column of the table that keeps data vertically, and the row is used to store it horizontally.
2) What associates with all information about every entry in the table?
Explanation: Column is used to store a piece of unique information associated with entries that can be anything such as id, name, number, etc. Key is just a constraint to find anything in relation, and a row shows all the attributes associated with entries.
3) In relation to a table, what term is used to refer single row?
B. Relation Instance
Explanation: Its answer is A because a tuple is a single entry that shows all attributes associated with the entry in a table.
4) The attributes of the table is referred to as:
Explanation: The column is referred to as an attribute of a table that contains the unique information associated with an entry.
5) Relational algebra is a ______ which takes instances of relations as input and yields instances of relations as output.
A. Relational query language
B. Structural query language
C. Procedural query language
D. Fundamental query language
6) Choose the correct option:
A. Set intersection is the fundamental operation in relational algebra.
B. An assignment is a fundamental operation in relational algebra.
C. Select is the fundamental operation in relational algebra.
D. Rename operation is the fundamental operation in relational algebra.
Answer: c and d
Explanation: The correct answer is C and D. Because Select, Project, Union, Set different, Cartesian product, and Rename is considered as fundamental operations in relational algebra while Set intersection, Assignment, Natural join is an additional operation in relational algebra.
7) Which language is used to define the database?
Explanation: DML(Data manipulating language) is used for accessing and manipulating the data, DCL(Data control language) is used for retrieving the stored data, and TCL(Transactional control language) is used for changes made by the DML statement.
8) Which of the following can be considered as the primary key?
B. Roll no.
Explanation: The attribute associated with the primary key should be unique. In any class, more than one student can have a common name, more than one student can get equal marks in any subject, and their street can also be common. So here, the roll number can be considered as the primary key.
9) The overall description of the database is known as:
A. Data manipulation
B. Database schema
C. Data definition
D. Data integrity
10) A boy name X has rupees 1000 in their bank account. His friend Y needs rupees 200, so he tries to make a transaction. He asks his bank to make the transaction to his friend’s account. After filling all the details and successful transaction, 200 is deducted from X’s account. But his friend Y told him that he doesn’t receive the money. What property of transaction has not been maintained here?
Explanation: The correct answer is A because atomicity means data should remain atomic. It means that whenever an operation starts, it should execute fully. The operation should not break in the middle or execute partially.