One of the things I have really enjoyed in my projects is writing SQL queries. It might even be my favorite language. Over time I got quite good at it, and it served me well in my career.

Depending on the role you are interviewing for you might be expected to demonstrate knowledge of SQL. Couple of popular questions are:

• What is the difference between SQL and NoSQL (we all know this, right?)
• Write a SQL query to retrive...

If you have no knowledge of SQL you should start with a tutorial like this and get some practice in.

But here is the thing with SQL: The basics are straightforward, but in your interview they will be looking for something a bit more complex. For that go ahead and bookmark => The Best Medium-Hard Data Analyst SQL Interview Questions

With that, you should be in a good spot to tackle the SQL questions.

Good luck!