Database Administrator (DBA) interview questions and answers

10 good database administrator (DBA) interview questions

1. How would you transfer data from MySQL to Microsoft SQL Server?
2. Would you run a test on a live database? Why or why not?
3. What measurements would you take to protect our databases from external threats?
4. We are building a new database for our employee records. How do you define system storage requirements?
5. How regularly would you perform tests to ensure data privacy?
6. Are you familiar with SQL? Name the most useful SQL queries and their roles.
7. What is the difference between navigational and relational databases?
8. Can you provide an example of where you can or should use a foreign key?
9. What is the difference between T-SQL and PL/SQL?
10. How can you identify if a database server is running properly?

Here are 10 essential interview questions and sample answers to help identify the best candidates for this role.

1. How would you transfer data from MySQL to Microsoft SQL Server?

This question assesses the candidate’s experience and knowledge in data migration between different database systems.

Sample answer:

“I would use a combination of tools like SSIS (SQL Server Integration Services) and scripts to transfer data. First, I’d analyze the schema in both databases to identify any compatibility issues. Then, I’d proceed with the data transfer, ensuring data integrity is maintained.”

2. Would you run a test on a live database? Why or why not?

This question gauges the candidate’s understanding of best practices in database management.

Sample answer:

“No, running tests on a live database is risky and not recommended. I would use a staging environment that mimics the live database for all testing purposes.”

3. What measurements would you take to protect our databases from external threats?

This question evaluates the candidate’s expertise in database security.

Sample answer:

“I would implement multiple layers of security such as firewalls, encryption, and regular audits. I’d also restrict user permissions to limit data exposure.”

4. We are building a new database for our employee records. How do you define system storage requirements?

This question tests the candidate’s ability to plan and implement new databases.

Sample answer:

“I would start by estimating the volume of data, considering growth over time. Then, I’d look into the types of queries and transactions to determine the required performance. Based on these factors, I’d define the storage requirements.”

5. How regularly would you perform tests to ensure data privacy?

This question assesses the candidate’s commitment to maintaining data privacy.

Sample answer:

“I would perform regular audits and tests, at least quarterly, to ensure that all security measures are effective and up-to-date.”

6. Are you familiar with SQL? Name the most useful SQL queries and their roles.

This question assesses the candidate’s familiarity with SQL, a fundamental skill for any DBA.

Sample answer:

“Yes, I am familiar with SQL. The most useful queries include SELECT for data retrieval, INSERT for adding new records, UPDATE for modifying existing data, and DELETE for removing records. These are the CRUD operations essential for database management.”

7. What is the difference between navigational and relational databases?

This question tests the candidate’s understanding of different types of database models.

Sample answer:

“Navigational databases use pointers to navigate through data, while relational databases use tables to define relationships between data. Relational databases are more flexible and easier to query.”

8. Can you provide an example of where you can or should use a foreign key?

This question evaluates the candidate’s understanding of database relationships and integrity.

Sample answer:

“A foreign key is used to establish a relationship between two tables. For example, in a database containing ‘Employees’ and ‘Departments’ tables, the ‘DepartmentID’ in the ‘Employees’ table could be a foreign key referencing ‘Departments.'”

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

This question gauges the candidate’s familiarity with database-specific SQL extensions.

Sample answer:

“T-SQL is an extension of SQL for Microsoft SQL Server, while PL/SQL is for Oracle databases. Both offer procedural programming features, but they have different syntax and capabilities.”

10. How can you identify if a database server is running properly?

This question assesses the candidate’s ability to monitor and maintain database health.

Sample answer:

“I would look at several factors like CPU usage, memory usage, and query performance. Regular logs and alerts also provide valuable information. If all these are within optimal levels, the server is likely running properly.”

What does a good Database Administrator (DBA) candidate look like?

A good DBA candidate should have a strong technical background, including expertise in SQL and various database systems. They should also have a deep understanding of database security and be able to communicate effectively with non-technical team members.