Top Database Interview Questions You Should Prepare for Technical Interviews
Most people struggle with database interview questions because they test your problem-solving abilities, accuracy, and attention to detail.
So, if you want to secure your future in the demanding field of database administration, prepare for the interview by reading this article. It covers the most important database interview questions and answers, which will help you improve your interview preparation for top software companies.
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The database interview questions are divided into several categories based on job roles. The upcoming segment will cover essential database interview questions and answers categorized under the following sections:
- General Database Interview Questions and Answers
- Database Interview Questions and Answers on Testing
- Database Interview Questions and Answers for Engineers
- Database Interview Questions and Answers for Senior Developers
- Database Interview Questions and Answers for Managers
- Additional Sample Database Interview Questions
- FAQs About Database Interview Questions
General Database Interview Questions and Answers
This section covers the most commonly asked general database interview questions:
Q1. What do you understand about BCNF?
BCNF refers to the Boyce Codd Normal Form, an advanced version of the third normal form that does not feature overlapping candidate keys.
Q2. Explain about RDBMS
RDBMS or Relational Database Management System is a relational data model that stores and gives access to data points. These data are represented through separate tables and related to the usage of a common column. Software developers can access this relational database through SQL or Structured Query Language.
Q3. What is DBMS, and mention some of its advantages?
DBMS, also known as Database Management System, is a collection of application programs. It allows users to organize and restore data effectively. Popular DBMSs include Oracle, MySQL, Sybase, etc.
Some of the advantages of DBMS are as follows:
- Data is organized in a structured manner; hence it keeps a check on redundancy
- It verifies the data that is collected and restricts unauthorized access to such stored information
- It offers backup and restores data when needed
- DBMS offers various user interfaces
Note - Make sure that you explain the advantages while answering such database interview questions.
Q4. Explain data redundancy.
Data redundancy is the duplication of information. The duplicate information wastes storage space and destroys the integrity of a database.
Q5. What do you understand about normalization and denormalization?
A process of eliminating redundant information from the database is known as normalization. Software developers split the table to maintain data integrity and save storage space.
Database Interview Questions and Answers on Testing
Whether you are a fresher or experienced tester, go through the following database interview questions that will help you crack your upcoming interview:
Q1. What do you understand by database testing?
Database testing is also known as backend testing and features three categories:
- Testing of data integrity and validity
- Performance of database
- Testing of procedure, functions, and triggers
Q2. What do you understand by a data-driven test?
The data-driven test checks the multiple numbers of data in a table. It replaces the parameters from distinct locations at the same time.
Q3. What do you understand about Joins? Mention the types of join
Joins exhibit two or more than two tables and are primarily of four types:
- Inner Join
- Outer Join and this further categorized into two types - right outer join and left outer join
- Natural Join
- Cross Join
Q4. What are indexes and their different types?
The database objects are indexes and are generated on columns. Different types of indexes are:
- Clustered index
- Covering index
- Bitmap index
- Unique index
- Non-unique index
- B-Tree index
Q5. How can we check SQL queries in QTP without utilizing database checkpoints?
We should write a scripting process in VBScript to connect with the database and test the SQL queries.
Database Interview Questions and Answers for Engineers
If you aspire to become a database engineer or want to progress from an experienced database or data engineer to a higher hierarchy, prepare the following database engineer interview questions:
Q1. What do you understand by data modeling?
Data modeling involves a process of producing a visual representation of an overall information system or its part to connect structures and data points.
Q2. What are the types of design schemas in data modeling?
There are two types of design schemas, snowflake, and star schema, in data modeling.
Q3. What do you mean by NameNode?
NameNode stores information and checks multiple files across clusters. The actual data is not collected here and is stored in DataNodes.
Q4. What do you understand about Hadoop streaming?
It is a feature of Hadoop distribution that allows software developers to write Map-Reduce programs by utilizing various multiple programming languages such as Peal, Python, C++, etc.
Q5. What do you understand by block and block scanner in Hadoop Distributed File System?
Hadoop splits large files into the smallest data units, known as blocks. Block scanner checks the list of blocks available in DataNode to identify checksum errors.
Database Interview Questions and Answers for Senior Developers
Q1. What do you mean by SQL injection?
Black-hat hackers use the SQL injection technique that hacks the data from databases or tables.
Q2. Explain about trigger in SQL
Trigger in database refers to the stored program. This automatically responds to the operations of DML by inserting, deleting, or updating.
Q3. How can you add several rows in Structured Query Language?
We can use the following syntax to add several rows in Structured Query Language:
INSERT INTO table_name (column1, column2,column3...)
(value1, value2, value3…..),
(value1, value2, value3….),
(value1, value2, value3);
We will add the keywords ‘INSERT INTO’ and enter the table’s name to add values. It will be followed by column lists and adding values for them. Then we will type the keyword ‘VALUE’ and provide the list of values.
Q4. Can you get the nth highest salary in Structured Query Language?
Here’s how we can get the nth highest salary in SQL SERVER by utilizing the TOP keyword:
SELECT TOP 1 salary FROM ( SELECT DISTINCT TOP N salary FROM #Employee ORDER BY salary DESC ) AS temp ORDER BY salary
To get the nth highest salary in MYSQL, we can use the LIMIT keyword. Here’s the solution:
SELECT salary FROM Employee ORDER BY salary DESC LIMIT N-1, 1
Q5. How can you insert a new column in the Structured Query Language?
By using alter command, we can insert a new column in the Structured Query Language:
ALTER TABLE employees ADD COLUMN contact INT(10);
You can also refer to top advanced SQL interview questions and answers to prepare for database interview questions.
Database Interview Questions and Answers for Managers
Take a look at the database interview questions to get yourself ready for the interview for the database manager:
Q1. Tell us something about yourself?
This is the most commonly asked question yet an important one. Keep your answer crisp yet relevant to the job you are being interviewed for. In addition to this, emphasize your education, work experience, additional interests beyond work, etc.
Q2. Can you brief us about your management style as a database manager?
Try to answer this question based on situations since it displays your strength as managing a team based on each situation.
Q3. Can you tell us which diagnostic test you use to check the performance of the database?
Highlight your expertise and knowledge in monitoring the performance metrics of a database.
Q4. How can you protect databases from hackers?
Learn about the security guidelines and procedures to answer this question without errors.
Q5. What is the best method to train junior developers?
You can answer this question based on your previous working experience displaying your mentorship capabilities.
Now that you already know about the common database interview questions for engineers, managers, and senior developers, scroll down and look at a few miscellaneous interview questions on database.
Additional Sample Database Interview Questions
Practice these sample database interview questions to perform well during your next tech interview:
- Explain types of relationships in the database
- What do you understand about SQL?
- Explain DML compiler
- How can you utilize SQL queries in QTP?
- Explain the method of writing test cases for database testing
- How can check the database triggers and procedures
- Can you mention the two messages that NameNode receives from DataNode
- What are the features of Hadoop?
- What is a star and snowflake schema?
- How can you find duplicate records in Structured Query Language?
- What do you understand by a cursor in SQL? How many types of cursors are available in SQL?
- How can you create an index in Structured Query Language?
- How can you shift data to MYSQL from Microsoft to SQL Server?
- Explain the differences between PL/SQL and T-SQL
- What is an efficient process to save and access files in databases?
- Mention a few commands of DML, DCL, and DDL.
- Explain the DDL interpreter.
- What are the advantages of SQL?
- Explain Field, Table, and Record in database.
- What is data independence?
- Mention two types of data independence.
- What is the relationship between data independence and view?
- Mention the pros and cons of views in the database.
- What is a functional dependency?
- Define the E-R model.
- Define Entity, Entity set, and Entity type.
- What is a weak Entity?
- What do the terms ‘Relations’ and ‘Attribute’ mean?
- Define SDL and VDL.
- Define database transactions.
FAQs on Database Interview Questions
Q1. What programming languages besides SQL must you know to crack the database interview questions?
To crack a database interview, you must be skilled with programming languages such as R and Python, besides SQL.
Q2. What advanced SQL questions must you prepare for technical interviews?
You must know the concepts of SQL like a key, stored procedures, parameters, commands, and functions. Besides, you must be adept at writing queries to organize and restore data from the database to prepare for technical interviews.
Q3. How to prepare for the basic database interview questions?
Q4. What are the four contents of a database?
The four database contents are data, procedure, hardware, software, and database access language.
Q5. What are the six database objects?
The six objects in a database are relationships, tables, queries, macros, forms, and reports.
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