Judge SQL courses by queries written, not hours watched
SQL is a small language that rewards repetition. The skills an analyst uses most, filtering, joining, grouping and aggregating, only stick when you write and debug many queries against tables you did not design. A course that is mostly video can leave you able to recognize a JOIN but not write one under time pressure.
So the first question for any option is where the queries run and how many you write. Browser-based exercises remove setup friction for a beginner. A local database such as PostgreSQL adds setup but lets you load your own data, which is what you will do at work. The best route usually uses both: browser practice to learn syntax, then a local database for a real project.
Three routes compared
None of these pages publishes a total query count, so treat the lesson, quiz and assignment numbers as a rough proxy. A quiz checks recognition; a coding assignment or exercise checks whether you can write the query.
| Option | Where queries run | Practice structure (from official pages) | Certificate | Cost on October 30, 2026 |
|---|---|---|---|---|
| SQLBolt | In the browser | Numbered lessons from SELECT basics to creating, altering and dropping tables; each lesson ends with an interactive exercise; extra topics on subqueries and unions | None listed | No price shown on the lesson index |
| PostgreSQL tutorial (official docs) | Your own PostgreSQL install | Three chapters: getting started, the SQL language (tables, queries, joins, aggregates, updates, deletes), advanced features (views, foreign keys, transactions, window functions) | None | Openly published documentation |
| Alison: SQL for Beginners | Video course; outcomes include installing SQL on a computer | 3 to 4 hours of video; schema, keywords, operators | Optional paid certificate; CPD-accredited | Free to study; certificate price not shown on the course page |
| Educative: An Introductory Guide to SQL | In the browser | 98 lessons across 11 modules, 78 quizzes, listed at 13 hours; joins, nested queries, views, stored procedures, transactions, indexes | Certificate of completion | Not marked free on the course page; price not shown on the pages we checked |
| Coursera: SQL for Data Science (UC Davis) | Course assignments | 4 modules, 15 assignments including coding assignments and a final project; module estimates total about 15 hours | Shareable certificate | Included with Coursera Plus, $59 a month or $399 a year |
Who should pay, and for what
Skip paid options if the main reason is the certificate and no employer or school has asked for one. A query project you can show is easier for a hiring manager to judge than a completion certificate.
- Pay nothing yet if you are exploring whether you like data work. SQLBolt plus the PostgreSQL tutorial covers the core language and gives you a real database.
- Consider Educative if you want a long run of short in-browser lessons and quizzes without installing anything, and you can finish within one billing period. Its pricing page says cancelling stops renewal but no refund is issued for the current period.
- Consider Coursera if you want graded assignments, a final project and a shareable certificate from a university-branded course. The annual plan has a 14-day money-back guarantee; the page does not state refund terms for monthly billing.
- Consider Alison if you need a free course with a CPD-accredited certificate for a training record and are prepared to pay only for the certificate. Alison says studying and completing courses is free and offers a free Learner Record as proof of completion.
A four-week plan ending in an original analysis
If you take a paid course, replace weeks 1 and 2 with its lessons but keep weeks 3 and 4. The original project is what shows you can work without a pre-built exercise. Our course project checklist explains how to make that project credible to a reviewer.
| Week | Learn | Practice target | Output |
|---|---|---|---|
| 1 | SELECT, WHERE, ORDER BY, LIMIT, NULL handling | Every exercise in the free tutorial for these topics, then 15 queries of your own on the same tables | A notes file of patterns you got wrong |
| 2 | Joins (inner and outer), aggregates, GROUP BY, HAVING | Rewrite each tutorial exercise a second way, for example a join as a subquery | Ten questions answered with joins and grouping |
| 3 | Install PostgreSQL; create tables, insert and update rows; views and window functions from the official tutorial | Load one public dataset you care about into your own tables | A schema and a cleaned table |
| 4 | No new syntax | Write 8 to 12 queries that answer one question about your dataset | A one-page write-up with queries, results and limits |
Worked example: one month of paid study (illustrative plan)
A learner wants a certificate and plans to finish SQL for Data Science in four weeks at about four hours a week, roughly the 15 hours the module estimates add up to. On Coursera Plus monthly, that is one $59 payment if they finish within the month and cancel before renewal. If they slip into a second month, the cost is $118. The $399 annual plan only makes sense if several other included courses are on their calendar for the year.
The same learner could do weeks 1 to 4 of the plan above at no cost and add the course only if they want graded assignments and the certificate. Either way, the week 4 project is the part that demonstrates skill.
Common mistakes
- Watching videos for a week before writing a query.
- Only running exercises on tables designed to make the answer neat; real data has blanks and duplicates.
- Treating quiz scores as proof you can write joins from scratch.
- Starting a monthly subscription before you have the hours free to use it.
- Skipping the write-up; a query without a stated question and result is hard for anyone to evaluate.
Questions before you decide
Can I learn SQL online for free?
Largely, for the core language. SQLBolt's interactive lessons, with no price shown on its lesson index, run in the browser and cover queries, joins, aggregates and table changes, and the official PostgreSQL tutorial covers the SQL language plus views, transactions and window functions on your own installation. Paid courses add structure, grading and certificates.
Is a SQL certificate worth paying for?
Only when someone asks for it or you want graded assignments. Coursera's SQL for Data Science includes a shareable certificate and is included with Coursera Plus at $59 a month; Alison courses are free to study with an optional paid certificate. A project with your own queries is easier to evaluate than either.
Do I need to install a database to learn SQL?
Not at first. SQLBolt and Educative's SQL course run queries in the browser. Installing PostgreSQL becomes useful once you want to load and analyze your own data.
Sources & verification
Product details and prices can change. Check the linked provider before buying.
- SQLBolt: interactive SQL lessons Accessed 30 Oct 2026
- PostgreSQL documentation: Part I. Tutorial Accessed 30 Oct 2026
- Alison: SQL for Beginners Accessed 30 Oct 2026
- Alison Help Center: is Alison really free? Accessed 30 Oct 2026
- Educative: An Introductory Guide to SQL Accessed 30 Oct 2026
- Educative: pricing and cancellation terms Accessed 30 Oct 2026
- Coursera: SQL for Data Science (UC Davis) Accessed 30 Oct 2026
- Coursera Plus pricing Accessed 30 Oct 2026
Sources link directly to providers. Product buttons may use separately labeled affiliate links. Read our disclosure.