Top Database Administrator (DBA) Interview Questions for 2023

Organizations all across the world rely on data to better understand their customer’s preferences and needs. Today’s businesses are collecting data at an unprecedented rate and this has increased the demand for database administrators (DBA) who can store, organize, and retrieve data when required for making business decisions.

If you are heading for a database administrator interview, preparing for the interview will increase your hiring chances immediately. In this blog, we have compiled the most frequently asked database administrator interview questions that an interviewer might ask you during your interview.

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Database Administrator Interview Questions

Database administration is an important component of the IT environment for any organization that relies on data. While interviewing for a DBA role, recruiting managers will test your knowledge by asking a variety of questions, so every candidate must prepare them before an interview. The following list of the commonly asked database administrator interview questions and answers for freshers and experienced candidates will help you ace your next DBA interview.

The DBA interview questions in this blog are divided into the following categories

• Technical Interview Questions
• Situational Interview Questions
• Behavioral Interview Questions

Technical Database Administrator Interview Questions

These questions include the role-specific, operations, and situations questions that will test your technical knowledge and skills in a database environment.

Q1. What is SQL? Name the most common SQL queries.

Ans. SQL stands for Structured Query Language. It is a popular programming language used for accessing and modifying data in databases. We can use SQL to insert, search, update, and delete records in a database.

Some of the most common SQL queries include:

SQL Query	Description
CREATE	to create a new database or table
SELECT	to view all records from a table
INSERT	to insert records into a table
DROP	to delete a database or table
UPDATE	to modify an existing table and update it with new data based on certain conditions
DELETE	to remove the records from a table based on certain conditions
WHERE	to filter results based on a specified condition
GROUP BY	arranges identical data from different rows into groups

Q2. Explain ODBC.

Ans. ODBC is short for Open Database Connectivity. It is an open standard API (Application Programming Interface) that helps in accessing a database. It is independent of platforms and operating systems. ODBC statements in a program enable users to access files in many different common databases. While working with the ODBC software, a separate module or driver is required for each database to be accessed.

The architecture of ODBC-based data connectivity consists of the following components:

• ODBC Enabled Application
• ODBC Driver Manager
• ODBC Driver
• Data Source

Also Read: Top Database Interview Questions and Answers

Q3. Explain SQLOS.

Ans. The SQLOS is a different application layer at the lowest level of the SQL Server Database Engine. It is the server application that manages the operating system resources. The SQL Server and SQL Reporting Services both run over it.

The main functions of the SQLOS include:

• Scheduling
• Synchronization
• Asynchronous IO
• Memory management
• Deadlock detection and management
• SQL server exception handling
• Hosting services for external components

Q4. What is the difference between T-SQL and PL/SQL?

Ans. T-SQL stands for Transact-SQL and is the extension of Structured Query Language that is used in Microsoft. PL SQL is short for Procedural Language Structural Query Language. It is the extension of Structured Query Language that is used in Oracle. Below are the differences between T-SQL and PL/SQL.

T-SQL	PL/SQL
The full form of T-SQL is Transact Structured Query Language.	PL SQL stands for Procedural Language Structural Query Language.
It works best with the Microsoft SQL Server.	It works best with the Oracle Database Server.
Easy to understand.	Hard to understand.
Gives a great degree of control to programmers.	Integrates well with SQL.

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Q5. Explain the difference between navigational and relational databases.

Ans. The main difference between navigational and relational databases is that in a navigational database, data is accessed by defining the path to find the required data while in a relational database, we can access data by stating what we want. Navigational databases may have hierarchical (one-to-many) or network (many-to-many) structures. They are mostly used for applications that need rapid data access.

Q6. Explain DBCC.

Ans. DBCC refers to Microsoft SQL Server Database Console Commands. The DBCC statements are used for performing a variety of tasks, such as ensuring the integrity of a database, performing maintenance operations on databases, and gathering and displaying information.

• Maintenance commands: for performing maintenance activities on a database, index, or filegroup.
• Informational commands: for collecting and displaying information.
• Validation commands: for validating the database.
• Miscellaneous commands: for miscellaneous tasks such as removing a DDL from memory.

Q7. What is a Join clause?

Ans. Join is a clause in SQL that helps to simultaneously search across multiple tables. Join helps in combining one or more than one table into a new table. There are different types of Join including (INNER) JOIN, LEFT (OUTER) JOIN, RIGHT (OUTER) JOIN and FULL (OUTER) JOIN.

Situational Database Administrator Interview Questions

Now, let’s take a look at some of the most important situational Database administrator interview questions:

Q8. What types of databases do you work with?

Ans. This question will be asked to check how familiar you are with different database servers and your level of expertise. The recruiting manager will ask this question to ascertain if you have the background they are looking for.

There are different types of databases such as Relational databases, Hierarchical databases, Network databases, Object-oriented databases, Graph databases, Document databases, NoSQL databases, and more.

You can frame your answer by telling the interviewer about the databases that you have worked with. For example, if you have worked with MySQL or Oracle, then you must share how proficient you are with these database servers and also share your level of expertise.

Must Read: 100+ SQL Interview Questions and Answers

Q9. How will you handle data loss during a database migration?

Ans. Every enterprise deals with data migration at some point. Data migration is a challenging process as if goes wrong, it can lead to downtime, exceeding budget, and delays.

Database administrators often face stress during times of database migration. The interviewer may ask this question to check how well you behave under pressure in such situations.

To answer this question, you can share:

• The strategies and techniques you use to overcome such situations
• Your understanding of how to troubleshoot and recover data
• An example of a similar situation that you handled in the past

Q10. What process would you follow to troubleshoot database problems?

Ans. Database administrators are expected to perform the troubleshooting task regularly and efficiently. To answer this question, you will need to share a well-defined process that you follow. You can share in detail your previous experience of how often you performed the troubleshooting task, what the process is like, and what resources and tools you used for troubleshooting.

Example: Here’s a basic process to troubleshooting SQL server problems

1. Gather facts and information
2. Test in a variety of environments and machines
3. Review the SQL Server error log
4. Review the event log
5. Review the default trace
6. Review the change log
7. Develop a plan for testing
8. Backup database
9. Additional testing and logging

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Q11. What steps would you take to protect the company’s databases from external threats?

Ans. This question will be asked to assess your knowledge and experience in safeguarding a company’s databases from cyberattacks and threats.

Due to increasing cyberattacks involving malware, phishing, and more, the data and assets of corporations, governments and individuals are at constant risk. Regardless of how big the business is, every company must protect its databases from any type of threat. Some of the common strategies to safeguard databases from external threats include:

• Deploying physical database security
• Setting up an HTTPS proxy server
• Using separate database servers
• Deploying data encryption protocols
• Using real-time database monitoring
• Avoiding the use of default network ports
• Using database and web application firewalls (Packet filter firewall, Stateful packet inspection (SPI), Proxy server firewall)
• Ensuring regular backups of the database
• Using strong user authentication
• Keeping applications up to date

Q12. What is the first step to deal with a lost database?

Ans. The first step is to restore the most recent consistent state just before the database was lost.

Q13. What is the use of recovery-only database restore?

Ans. Recovery-only database restore can be used in two situations when:

1. You were unable to recover the database while restoring the last backup in the restore sequence and you want to recover it to bring it online.
2. Database is in the standby mode and you want to ensure that the database is updatable without applying other log backup.

Q14. What is a clustered index in a database?

A clustered index in a database determines the physical order of the data rows in a table based on the values of one or more columns. Unlike non-clustered indexes that create a separate structure, a clustered index directly sorts and stores the table’s data rows. Each table can have only one clustered index, and it impacts the way data is stored on disk, affecting the table’s retrieval and storage performance.

Q15. What is a foreign key constraint in a database?

A foreign key constraint in a database is a rule that enforces the referential integrity between two tables. It establishes a relationship between a column (or set of columns) in one table, known as the foreign key, and the primary key column(s) in another table, known as the referenced key. The foreign key constraint ensures that values in the foreign key column(s) of a table must match the values in the referenced key column(s) of the related table or be NULL.

Behavioral Database Administrator Interview Questions

Here are some frequently asked behavioural Database administrator interview questions:

Q1. Share what was your role in the most challenging project you worked on.

Q2. How do you learn about new applications?

Q3. Share the time when you implemented a solution that improved data storage.

Q4. How regularly will you carry out tests to ensure data privacy?

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Conclusion

This brings us to the end of our blog on Database Administrator interview questions. We hope the interview questions in this blog will help you prepare better for your next interview so that you can clear it in the first attempt.