The interview included three SQL questions, followed by three Python questions. You were allowed to code on a screen and run your code as many times as needed.

Both sets of questions were very easy. I could have answered them fifteen years ago. With eight years of experience as a data engineer, I'm unsure why I was asked to take such a basic test.

I consider the interview process difficult because all coding tests present challenges. You must answer questions within a short timeframe. If you were familiar with the data and problems as you would be at work, these questions would be easy. However, in these tests, you are trying to understand both the problem and the data.

In SQL, you had to use a CTE and then a final query to filter out items. I did this correctly, but then I encountered a Cartesian join. I couldn't start debugging within the limited time frame. The fix was to use WHERE x IN (SELECT x FROM cte1). This was trivial, yet it consumed valuable time and made me feel foolish when the problem was so simple.

In my case, I had to dynamically format a SQL string. This is extremely trivial, and I had the correct method, but it didn't register correctly because there was a space at the end of my SQL string. Additionally, it wasn't quite right because I formatted the strings with double quotes instead of single quotes. The parameter passed to the function was "", when it should have followed Python standards of None. These minor issues tripped me up, and I ended up burning a lot of time on small details.

SQL: Count the number of items in a certain range (use SUM(CASE WHEN x < 100 THEN 1 ELSE 0 END) AS under_100, etc.)

Python: Join 2 lists and sort (This just involves one line of code, so I was surprised)

Python: Remove items with a certain key

Python: Dynamically format SQL depending on the parameters passed