💻 The Only SQL Interview Guide Data Engineers Need

So you’re prepping for a data engineering interview, right?

Whether it’s your first break or you're aiming for a top-tier company, SQL is always part of the game. And we’re not talking just basic SELECT statements — interviews go deep with window functions, tricky joins, subqueries, and more.

I created this guide to help you skip the random Google searches and practice the right problems — all organized by topic and difficulty, with direct links.

Why This Blog Exists

When I started preparing, I had 15 tabs open, from LeetCode to HackerRank to Excel sheets with broken links.
It was chaos.

So I organized everything into one solid resource — this blog.
Every problem here is hand-picked, categorized properly, and linked for easy practice.

Beginner SQL Questions

These are the building blocks. Even if you’re experienced, interviewers still love throwing these in to test your basics.

Start with simple SELECTs:

• Select All

• Select By ID

• Japanese Cities' Attributes

• Weather Observation Station 1

• Weather Observation Station 3

Filtering and conditions:

• Higher Than 75 Marks

• Employee Names

• The PADS

• Binary Tree Nodes

Intermediate SQL: Aggregations, Joins & Subqueries

These are the “real-world” problems. You’ll see them often in actual pipelines and in interviews.

Aggregation functions:

• Count Function

• Average Population

• Top Earners

• Weather Observation Station 5

• Weather Observation Station 14

Joins and project-style queries:

• SQL Project Planning

• Asian Population

• Japan Population

• Population Density Difference

Subqueries you should master:

• The Report

• The Report 2

• Print Prime Numbers

Advanced SQL: Window Functions, Rankings & Analytics

These are the toughest ones — and the most interesting.

Analytics & window functions:

• Rank Scores

• Department Top Three Salaries

• Sales Analysis I–IV

• Consecutive Numbers

Subqueries, puzzles & tricky joins:

• Symmetric Pairs

• Placements

• Type of Triangle

• Alien Username

Misc + leaderboard logic:

• Top Competitors

• The Blunder

• The Report 3 & 4

• Weather Observation Station 17–20

How to Use This List

• Practice 3–5 problems per day

• Try to explain your solution out loud

• Time yourself like a real interview

• Track your progress in Notion or Google Sheets

• Revisit your mistakes regularly

💡 Final Thoughts

SQL is more than just writing SELECT queries — it’s the tool behind everything from dashboards to machine learning pipelines.
If you're serious about becoming a better data engineer, mastering SQL is non-negotiable.

I hope this list helps you stay consistent, stay focused, and most importantly — stay confident.If you'd like a version of this blog as a PDF or Notion tracker, just drop a comment and I’ll hook you up!