12 SQL Query Interview Questions for Developers

Can you solve these 12 SQL query interview questions from coding interviews?

Hello guys, if you are looking for SQL query examples from interviews or SQL Query Practice questions to improve your SQL skill or just to prepare for tech interviews  then you have come to the right place.

In the past, I have shared Java Multithreading questions, Java Serialization questions, System Design interview questions and Enum Interview Questions and in this article, I am going to share 12 popular SQL query questions from interviews.

SQL is an important skills for both programmers and data scientist, even people from QA and BA stream also need to know SQL to do their job well in this era or data driven world. That's why SQL queries are also quite popular on interviews. 

If you have given interviews then you may have come across questions like how to find 2nd highest salary or Nth highest salary or remove duplicates form table.

These are classic SQL query questions and in this article, I am going to share few more question to prepare you for tech interviews. 

You can also practice them to test your SQL skills before your technical Interview. If you don't know SQL, a short form of Structured Query Language is one of the essential skills in today's programming world. 

No matter whether you are a Java developer, C++ developer or Python developer, you must know how to write SQL queries. Every programming job interview has at least one or two questions that require you to write SQL queries for a given requirement and many developers struggle there. 

It's easy to answer theoretical questions like how does SQL query work, or, what is the difference between clustered and non-clustered index or what is the difference between correlated and non-correlated subqueries ), but when it comes time to actually write SQL queries to solve problems, it's not that easy, especially if you haven't done your homework and practice.

In order to learn fast, start with a small table with a few columns which include data types like number, date, and String, which have fewer number data so that you can quickly understand and expect what should be output.

Includes some NULL, empty, and out of bound values to really test your queries.

Considering all these together today I am going to share SQL script to create a sample table to practice writing SQL queries for interviews.

In this article, you will find an SQL script to create a table and populate it with sample data and then write SQL queries to solve some common problems from Interviews.

By the way, if you are preparing SQL query, I also recommend you to checkout my book “Grokking the SQL Interview”, where I have share both theoretical and practical SQL questions and solutions. You can also use code friends30 to get 30% discount.

12 SQL Query Problems with Solutions for Technical Interview 

It's time to write SQL queries now. This section contains 6 SQL query Interview questions that will test many of your SQL skills like joins, grouping, and aggregating data, how you handle nulls in SQL etc.