Grokking SQL for Tech Interviews

Who gets asked SQL

More people than expect it. Data engineering and analytics roles obviously, but also backend and full stack loops, especially where the product is data heavy. The questions are rarely exotic: joins done correctly under time pressure, grouping with the right filter, and ranking or running totals.

What it covers

The course page lists 14 chapters, 123 lessons and about 20 hours of study time (September 2026). The structure:

• Introduction: what an RDBMS is and what SQL is.
• Quick review of SQL: SELECT, WHERE, operators, NULL handling, DISTINCT, ORDER BY, LIMIT and OFFSET, GROUP BY, HAVING and aggregate functions.
• Order of execution: why a query runs in a different order from how it is written, which explains many confusing results.
• Functions: number, string and date functions.
• Nested queries and types of subqueries.
• Joins: inner, left, right, full outer and self joins.
• Set operations: UNION, INTERSECT and EXCEPT.
• DDL and DML reviews: keys, CREATE, ALTER, DROP, TRUNCATE, indexes, INSERT, UPDATE and DELETE.
• Backup and restore.
• Interview problems: 34 easy, 20 medium and 15 hard lessons, each with an example, a solution query and a step-by-step explanation, then 14 Test Your Knowledge problems with no hint about which technique applies.

Queries run against a live database in the browser, so you see real rows come back.

Is it worth it?

As of September 2026 the course page lists a one-time price of $99.90 for lifetime access, and it is included in the provider's all-courses subscription. It shows a 4.2 rating from about 3,450 ratings and roughly 14,300 learners.

The course brings the review, the explanations and the graded problems together in one ordered path, running against a real database, so you can go from rusty to interview-ready without assembling material yourself.

How long it really takes

Two weeks at an hour or two a day is realistic: a few days for the review chapters, the rest for the problems. If you already write SQL at work, you can move quickly through the review and spend most of the time on the problem chapters.

How to use it well

• Type every query. SQL reads like English, which gives a false sense of fluency. Writing it is different.

• Predict the output of each join before running it, especially with NULLs and outer joins.

• Do the Test Your Knowledge set last, timed, without looking back at chapters.

Best for: backend, data and analytics candidates, and anyone whose SQL stops at a basic inner join.