Randstad Technologies has 35 years of experience recruiting for the IT sector, matching the right candidate with the best IT role. Part of the job hunting process calls on the candidate to perform well at the interview stage.

In order to help candidates throughout the preparation process, we gathered 70 commonly asked interview questions for SQL developer job candidates:

Technical SQL interview questions.

  1. Define DMVs.
  2. What is a temp table?
  3. Describe the difference between a local temp table and a global temp table.
  4. What is the purpose of transactions?
  5. Describe the difference between a clustered index and a non-clustered index.
  6. Define DBCC commands. 
  7. What is the difference between truncate and delete?
  8. For SQL Server, what is the default port number?
  9. Explain the difference between inner and outer join. Illustrate your answer with an example.
  10. Describe the difference between UNION and UNION ALL.
  11. Explain the difference between WHERE clause and HAVING clause.
  12. Describe Self Join and why it is important.
  13. Without ROWNUM, how do you generate a row number? 
  14. Describe the difference
  15. between ROWNUM pseudo column and ROW_NUMBER() function.
  16. To read data out of a table, what is the basic form of SQL statement?
  17. What structure can you apply to the database to speed up table reads?
  18. What are the disadvantages to having indexes?
  19. What is the difference between normalization and denormalisation? Under what circumstances would you want to denormalise? 
  20. What is the purpose of a constraint?
  21. What are the types of index structures you can have? Define primary key.
  22. Explain functional dependency and how it relates to database table design. What is the purpose of a trigger? Name the different types of Collation Sensitivity. 
  23. Explain the difference between a primary key and a unique key.
  24. Why would you use the UPDATE_STATISTICS command?
  25. State the authentication modes in SQL server and how they can be changed.  
  26. Explain Log Shipping.
  27. Describe some ways to get an accurate count of the number of records in a table?
  28. Explain what a FOREIGN KEY is.
  29. State the advantages of using Stored Procedures?
  30. If it has neither Cluster nor Non-cluster Index, what is a table called? What is its purpose?
  31. When did SQL appear?
  32. What uses does SQL have?
  33. State the subsets of SQL.
  34. Describe Data Manipulation Language.
  35. Describe Data Control Language.
  36. Describe Data Definition Language.
  37. How do you create a database?
  38. How do you select a database?
  39. How do you create a table?
  40. How do you delete a table?
  41. What is the EXPLAIN statement used for?
  42. Describe the difference between group by and order by.
  43. Describe a subselect and how it differs from a nested select?
  44. Is it possible for a Primary key to be a Foreign key on the same table?
  45. State the advantages of procedures.
  46. Define Parsing.
  47. Describe what a cursor is. 

Personal SQL interview questions.    

  1. What are your weaknesses?
  2. Describe yourself professionally in a few words.
  3. In our industry, what are some important trends that you see?
  4. What are your reasons for leaving your previous/present job?              
  5. What is your favourite aspect of being a SQL developer?
  6. How do you remain abreast of new developments in technology?
  7. Who else have you applied to/got interviews with?        
  8. Have you got any questions?
  9. Why should you get this job?

Scenario interview questions.

  1. What is your troubleshooting process?
  2. Would you describe yourself as a problem solver? If so, why? Can you give any example

Interview questions about the company.

  1. Why do you want to work for this organisation?     
  2. What do you know about our company and our products?   

Career-based SQL interview questions.

  1. In two or three years from now, what do you see yourself doing? 
  2. Describe two or three of your accomplishments over the past few years that you are most proud of.