20 Database Testing Interview Questions

By Indeed Editorial Team

Updated April 2, 2021 | Published February 25, 2020

Updated April 2, 2021

Published February 25, 2020

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Database testing is a complex skill to master which will likely present itself during interview process. Beyond social niceties and typical interview conversation, the questions you face for this role may be pretty specific to the role and require you to speak in depth in order to prove your comfort level in detail and with examples. In this article, we discuss some questions you may encounter along with tips and examples.

Related: Guide To Database Administrator Certifications

Interview questions with sample answers

Reviewing a list of potential questions of the specific and in-depth nature you'll hear in the interviewing process will work as a great refresher in addition to preparing you for talking points. Below are some common interview questions for the skill of database testing and advice on how to answer them.

  1. In your own words, describe database testing.

  2. Why is database testing important?

  3. Can you briefly explain the different types of database testing?

  4. Can you explain the general process of database testing?

  5. What is required to write a database test case?

  6. What do you check for when testing?

  7. How does manual testing work? Give an example.

  8. What is a trigger and how can you verify that it fires?

  9. How do you test database procedures and triggers?

  10. Can you list the steps required to test data loading?

  11. How do you test stored procedures?

  12. Can you define a data-driven test?

  13. What SQL statements can you use in database testing?

  14. What are the DDL commands in SQL?

  15. What are joins and what are the different types?

  16. What is an index and what are the different types?

  17. What is a view?

  18. Can you explain what DBMS is?

  19. Can you explain what DML is?

  20. Can you explain what normalization is?

Related: 14 Common SQL Interview Questions for Testers (With Example Answers)

In your own words, describe database testing

Asking an open-ended question about the skill itself gives interviewers a chance to assess your general knowledge on the topic. Try to give a short description of the skill, keeping your answer simple and broad.

Example: "I understand database testing as a layered process consisting of the user interface, business, data access and the database itself. It requires precision in table checking and writing queries to ensure that all actions run as intended."

Why is database testing important?

Not only does this question further assess your knowledge, it determines the value that you put on the skill. When offering your answer, explain in detail why you believe this is a vital skill to have.

Example: "Consistent database testing ensures that vital application functions run smoothly, guaranteeing successful transactions and properly stored information. Testing allows you to find and address problems as soon as possible."

Can you briefly explain the different types of database testing?

Now that you have established your general knowledge of database testing, the interviewer may shift to more specific questions, the goal being to determine if you can think fast and know the information well enough to provide a clear answer.

Example: "Testing is split into three categories. The first is structural database testing which deals with tables, columns and schema. The second is functional testing which requires us to investigate application functionality from the user perspective. The third is nonfunctional testing which involves various forms of stress and risk testing, determining minimum system requirements and assessing the overall performance of the database."

Can you explain the general process of database testing?

The interviewer wants to know if you can give an in-depth description of the process. This is another question in which you should provide explicit detail.

Example: "The first step is to set up a test environment with configurations for the hardware, software and network to function. It must be identical to the production environment for comparison. The second step is to perform test cases, looking for problems with transactions, schemas, triggers or stored procedures. The third step is to verify and validate results, comparing them to expected results as well as the live environment. The final step involves reporting the results to the appropriate party."

What is required to write a database test case?

On the job, you may be required to write test cases. The interviewer wants to know if you are familiar with the process.

Example: "To write a database test case, you must fully understand how the application works and what its functional requirements are. With that knowledge, you can confirm that the application uses back-end tables and the joins between them, cursors, triggers, stored procedures and input-output parameters. Then, you can then write the test case with different input values to examine each area."

What do you check for when testing?

You have outlined the process required in the previous question, now think back to the second step and go further.

Example: "During the test, you check the field size validation and constraints. You also determine whether or not indexes are done and if the field size defined in the application matches the database."

How does manual testing work? Give an example

Consider your previous experience in database testing and come up with a scenario in which you would conduct a manual test.

Example: "Testing a database manually involves using the application as the end-user would. You can compare your actions on the front-end to how they translate to the back-end. For example, if you are working with an application that stores data related to student grades, you can input a new grade on the front-end. From there, you can determine if the data was saved on the back-end and if it affected the student's average within the system."

What is a trigger and how can you verify that it fires?

Try defining the term simplistically, then give an example of how to verify a trigger.

Example: "A trigger is a type of SQL procedure that initiates a new action in response to an event. For example, if you must add a new student name to an application that records grades, you can verify on the back-end if the new name was added to its appropriate table as well as if new records were created for it."

How do you test database procedures and triggers?

Testing procedures and triggers is an essential part of database testing as a whole. With a question like this, be as detailed as you can. Walk your interviewer through the whole process.

Example: "To test procedures and triggers, you need to know the input and output parameters of the application. It's beneficial to understand what an EXEC statement is and how it allows you to run a procedure and observe table behavior. You begin by opening objects that need to be tested and create new unit tests for them. You then decide whether to use an existing test class or create a new one. Finally, you set the configurations for the project and run it. Monitoring events on the front-end with the corresponding table behavior on the back-end will either confirm or deny that triggers are functioning as intended."

Can you list the steps required to test data loading?

Just like with the previous question, be detailed and walk them through the process. The goal is to prove you know how to test data loading beyond a textbook definition.

Example: "To begin, you must obtain the source and target databases, then check the compatibility between them. The next step is to run corresponding DTS packages and compare the columns of your source and target databases. With that data, you can verify the number of rows and whether your changes have been implemented after the update. The final step is simply to verify null values."

How do you test stored procedures?

There are many processes involved in database testing, and this is another example of one you may be asked about. Use industry terminology and be specific if you have to.

Example: "It begins with understanding its requirement and purpose. Next, analyze all required components such as updates and deletions and determine if they match the tables in the procedure. Next, check a procedure's calling name and parameters as well as its expected responses. Finally, run the procedure with a program like MySQL. If the test goes well, you can rerun it with different parameters and compare the new results with the expected ones. Once complete, automate the test with a tool such as QTP."

Can you define a data-driven test?

Beyond lengthy procedures, you may be asked to simply define certain times of tests. For a question like this, keep your answer concise with two to three short sentences.

Example: "A data-driven test is like a framework that stores data in a table format. With a framework like that in place, you only have to use a single test script to execute tests for all the data in the table."

What SQL statements can you use in database testing?

This is another question related to terminology. Your interviewer wants to ensure you can accurately list the types of statements you will use on the job.

Example: "SQL commands are broken down into fif3 types: DDL, which is data definition language, DML, which is data manipulation language, DQL, which is data query language, DCL, which is data control language and TCL, which is transaction control language."

What are the DDL commands in SQL?

Knowledge of structured query language is a vital component of the role. You need to be familiar with these commands and be able to list them when asked.

Example: "DDL commands define the structure of the database. There are five commands in total: create, alter, drop, truncate and rename. Each one places the desired effect onto the database."

What are joins and what are the different types?

You will need to know the various terms related to the table structure. List the types in regard to SQL and be prepared to discuss Oracle and PSQL as well.

Example: "Joins combine multiple tables or displays into a single set of data. In regard to SQL, there are four types: inner, outer, left and right. Oracle and PSQL have similar types: inner, left-outer, right-outer and full-outer."

What is an index and what are the different types?

This is another term related to tables. Your interviewer may ask you to define it as well as its types. As with previous terms, keep your definition short and simple.

Example: "An index is a database object used to help find data more efficiently. There are six types of indexes: b-tree, bitmap, clustered, covering, unique and non-unique."

What is a view?

Programming can be complex, and there are multiple terms you need to be familiar with. This is yet another you may be asked to define. Remember that short definitions are best.

Example: "You can think of a view as a virtual table that mimics a real table. The fields laid out within the view are from real tables and don't contain their own data. Instead, they're used to restrict database access."

Can you explain what DBMS is?

If you are only given an acronym within the question, you need to be able to state its full name along with the definition. Be sure to provide examples of DBMS you are familiar with.

Example: "DBMS stands for database management system. It's an application that acts as an inter-user chat system and connects with other databases to store or modify information. A good example of a DBMS would be MySQL."

Can you explain what DML is?

Acronyms are prevalent in the programming industry. This is another one you may be asked about. Your definition should be short and concise, and you should state the full name of the term.

Example: "DML stands for data manipulation language and is used to insert, select, update and delete data within a database."

Can you explain what normalization is?

In regard to table maintenance, your interviewer may ask you about related terms such as this. Whether it was asked or not, be sure to list the different types along with your definition.

Example: "When you normalize a table's design, you're doing so to minimize redundancy within the data. In SQL, there are four different types of normalization: first normal, second normal, third normal and Boyce & Codd normal."

Related: 20 Database Testing Interview Questions

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