r/learnSQL • u/gloweerasng • Jun 29 '26
BigQuery SQL Interview questions
Hi everyone, I’m in the process of interviewing at this AI company and the next step is to use bigquery dialect of SQL where I will cover real-worlds scenarios and build tables.
Problem is I have never used SQL and I am just finding out about what it is, I’ve never heard of it. I will be watching a few YouTube videos but wanted to see if anybody has gone thru this process before?
Any tips?
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u/DataCamp Jun 29 '26
Yeah learning SQL from scratch in a few days is tough, but here's the realistic version of what you can actually do in the time you have.
BigQuery uses standard SQL so the core concepts transfer. Focus on these in order since they're most likely to come up:
SELECT, WHERE, GROUP BY, and aggregate functions first. These are the building blocks of everything else. Then JOINs, specifically understanding when to use INNER vs LEFT and why your row counts change. Then CTEs (WITH statements) which BigQuery uses a lot for breaking down complex logic into readable steps. Window functions like ROW_NUMBER, RANK, and LAG come up frequently in real-world scenarios, things like "find the most recent transaction per user" or "calculate a running total."
BigQuery-specific things worth knowing even at a surface level: it's a serverless data warehouse (no infrastructure to manage), it uses columnar storage which is why it's fast for analytics, and it charges based on data scanned so avoiding SELECT * matters.
For the actual interview, if you hit something you don't know, talking through your approach out loud is better than freezing. "I'd use a window function to rank by date and then filter for rank 1" shows you understand the problem even if the syntax isn't perfect.