Answer business questions directly in the database: querying, aggregation, joins without duplicated rows, CTEs, window functions, cohorts and funnels, and a guided customer and revenue analysis project.
Level
02
Modules
05
Lessons
21
Introduction
SELECT, WHERE and ORDER BY
Downloadable Assets and Resources
Expressions, NULL and CASE
Dates and Text in SQL
Reading Query Results Safely
Assessment
Company data lives in databases, and the fastest way to an answer is a query. But SQL has a nasty habit: a query can run without an error and still return the wrong number. This course teaches you to write SQL that is correct, readable and checked, and it is built around the mistakes that produce wrong results silently: the average that ignores NULL, the join that multiplies rows, the filter that quietly turns a left join into an inner join, the NOT IN that returns nothing.
There is no server to install and no account to create. The data is a single SQLite file, the online shop Trailhead Outfitters with 1,200 customers, 40 products, about 5,900 orders, their order lines and 29,540 website sessions, and you open it from Python in Google Colab or Jupyter. Because the data is the same shop as in the first course of the path, you already know what the numbers should look like, which makes checking a query easier.
Each lesson explains an idea with a short piece of theory (including the relational reasoning behind it), then shows real queries with their real results, then gives exercises with hints. You are encouraged to treat every query as a claim that needs a check, and you practice the checks: row counts, totals that must add up and independent computations.
The last module is a guided project: a customer and revenue analysis written entirely in SQL for a leadership meeting. It covers revenue by category and channel, customer value, cohort retention and the buying funnel. You get a brief, a starter notebook with ten milestones and 20 self-checks (it opens the database read-only, like a careful analyst working on production), and a worked solution to compare with.
Lessons on querying, aggregation, joins and window functions, ready-to-use SQLite data of the whole shop, a guided customer and revenue project with starter and solution notebooks, and a quiz for every module.
SQL is the skill that opens the most doors in data work, and most people learn it badly, from tutorials that never show what goes wrong. This course shows you exactly that, so your queries are trusted and your numbers hold up when someone checks them. If you work with company data, or want to, and you are done with wrong totals and mystery duplicates, this is the course to take. Enroll now and start writing queries you can stand behind.
SkillEnsure certifications are built around demonstrated competency and real-world capability beyond traditional course completion or attendance-based certificates.
The certification framework was straightforward and well-organized. I liked having access to knowledge references while still being able to prove my understanding through assessment.
The assessment criteria were clear, and the entire certification felt fair and transparent. It’s a system I can confidently showcase.
The certification process is well-defined and focused on actual performance. It’s not just theory, it’s proof of skill and expertise.
Many certifications focus on course completion. SkillEnsure focuses on demonstrating understanding against defined competency criteria, which made the credential feel more valuable to me.
