SQL is unavoidable if you work in data. In fact @LukeBarousse showed this when he analyzed well over 1 million jobs from indeed(image below)! Even with assistants like ChatGPT, I still need to write a lot of my own SQL. And whether you're a data scientists or data engineer you're going to have a SQL round in your interviews. So here are 9 concepts you should study for your SQL interviews. 1. Be able to explain the different types of joins. I have sometimes seen this question asked by recruiters as a screener question just to make sure they want to pass you along 2. Know when HAVING is run in SQL's order of operations vs WHERE 3.Know the difference between UNION and UNION ALL 4. Understand how to use a CASE statement inside of a SUM or COUNT function 5. Know at least 1-2 ways you could optimize a query and if you decide one of those answers will be put an index on the table..you should also know what the pros and cons of an index are 6. Be able to implement both a subquery and CTE, but use a CTE if you want to prove that you have good SQL habits 7. Know how to answer a problem with and without a window function. Usually you will need to implement a self join in order to imitate some window functions such as LAG and LEAD. 8. Understand and be able to explain what a correlated subquery is 9. Just reference that you would look at the query execution plan. They will be shocked you even know what that is. I would love to hear what questions you were asked your SQL interviews. Please share them below! #SQL #dataengineering #datascience Also, if you want to check out Lukes project, I'll link it in the next tweet