Grokking SQL for Tech Interviews

It is a SQL course built around interview questions rather than around a database syllabus. It reviews the language quickly, spends its time on the parts interviews actually probe such as joins, subqueries, set operations, and execution order, and then gives you 69 graded interview problems plus a 14 problem final check, all runnable in the browser.

Anyone facing a SQL round: backend and full stack engineers, data analysts, data engineers, business intelligence and analytics candidates, and product analysts. It also suits engineers who write SQL occasionally through an ORM and have never had to produce a correct query from scratch while somebody watches.

MySQL. The concepts and the vast majority of the syntax carry over directly to PostgreSQL, SQL Server, Oracle, and the cloud warehouses, since interview questions almost never hinge on a vendor-specific feature. Where a dialect would differ, it is usually a function name rather than an idea.

Yes. Problem lessons embed a live database, so you write your query, run it against real tables, and see the rows it returns before you look at the solution. That matters more in SQL than in most subjects, because a query that looks right and returns the wrong rows is the single most common way candidates fail this round.

No, but this is a fast review rather than a first tutorial. The early chapters cover the language from the ground up in about 10 lessons, then the pace picks up sharply. If you have never written a SELECT statement you will need to read those chapters slowly. If you have written SQL before and simply need to get sharp, you can start at the joins chapter.

The kind companies actually set, many of them recognisable from real interview loops: second highest salary, second degree followers, running totals, longest winning streak, human traffic of a stadium, trips and users, dynamic pivoting and unpivoting of a table, top achievers per subject, and a long run of product, game play, and employee reporting questions. They are graded easy, medium, and hard, and each one comes with a step by step account of how the query was assembled rather than just the finished answer.

Yes, and arguably more so. Analyst and data engineering loops often make SQL the main technical screen rather than one round among several, and the problem set here is aimed squarely at that style of question.

Roughly a third of it is a fast tour of the language: a quick review of SQL, execution order, functions, nested queries, joins, set operations, DDL, DML, and backup and restore. The rest is problems, split into easy, medium, and hard chapters, finishing with a Test Your Knowledge chapter that mixes them together without labels.

Text-based, with diagrams for the join behaviour and a runnable database on the problem lessons. Reading a query, changing it, and re-running it is the whole point, and that is a page interaction rather than a video one.

Yes. Design Gurus issues a certificate once you have completed the course, and you can share the link directly or add it to your LinkedIn profile.