Read a database
Identify tables, keys, relationships and the useful grain before writing a query.
Available learning pathBeginner to independent
SQL.tn learning path
SQL Foundations
Understand how a database is structured, then learn to filter, calculate, join and organise the data needed for a business decision.
No card required · 8 lessons · 15 exercises in the Discovery access
20structured lessons
44validated exercises
5progressive modules
2published business projects
Skills you will build
By the end of this path, you will be able to turn a question into a checked result.
Query precisely
Select, filter and handle missing values without changing the business question.
Calculate metrics
Group, aggregate and verify the totals used in a report or dashboard.
Join data
Choose a join, check duplicates and explain why the result can be trusted.
Structure an analysis
Use dates, subqueries and CTEs to build readable, reusable logic.
Deliver an answer
Turn a query into a concise conclusion with clearly stated checks and limits.
Full syllabus
A visible progression from the first table to a business project.
Every lesson states its objective, duration and access level. Paid content is never presented as free.
Module 1Understand and read dataTables, relationships and first selections · 4 lessons+
- 01Understanding a databaseLearn how tables, rows, columns and keys transform information into reliable data.
- 02Read data with SELECT and FROMChoose useful columns, identify the source table and make your results more readable.
- 03Filter with WHERE and sort with ORDER BYTurn a full reading into an accurate response with conditions and sorting.
- 04Master IN, BETWEEN and LIKEExpress lists, intervals, and text searches without piling on difficult-to-read conditions.
Module 2Filter accuratelyConditions, missing values and business choices · 4 lessons+
- 05Remove duplicates with DISTINCT and limit resultsGet a list of unique values and build a ranking that is short, stable and easy to verify.
- 06Handle missing values with NULL and COALESCEDetect missing information and replace it with a context-appropriate presentation value.
- 07Calculate with expressions and aliasesTransform source columns into directly usable amounts, ratios and labels.
- 08Clean and assemble textNormalize labels with TRIM, UPPER, LOWER, LENGTH and concatenation.
Module 3Calculate and summariseAggregations, groups and metrics · 4 lessons+
- 09Analyze dates and periodsFilter for an unambiguous period and build repeatable monthly indicators.
- 10Calculate indicators with COUNT, SUM and AVGTransform a set of lines into simple indicators: volume, total and average.
- 11Group with GROUP BY and HAVINGCalculate an indicator by category, city or status, then filter the resulting groups.
- 12Link tables with INNER JOIN and LEFT JOINAssociate customers with their orders without losing sight of the keys and scope of the result.
Module 4Join several tablesJoins, grain checks and result quality · 4 lessons+
- 13Connect three tables without multiplying rowsFollow the level of detail of an analysis across orders, order lines and products.
- 14Fix a problem with subquery and EXISTSBreak down a question into intermediate results and properly test for the existence of a relationship.
- 15Merge results with UNIONCombine lists compatible with UNION, UNION ALL, INTERSECT and EXCEPT.
- 16Check NULL, duplicates and consistencyTurn quality intuition into measurable, repeatable SQL controls.
Module 5Build a complete analysisDates, subqueries, CTEs and a reproducible method · 4 lessons+
- 17Structuring an analysis with CTE and CASEBreak a complex query into named steps and translate a business rule with CASE.
- 18Build a multiple analysis CTEBreak a complex analysis into named, testable, easy-to-read steps.
- 19Mini-project: analyze salesMobilize filters, aggregations and groupings to respond to a complete commercial brief.
- 20Final project: manage the e-commerce marginAssemble filters, joins, calculations, aggregations and controls to produce a business recommendation.
Guided project included
Finish with a complete analysis.
The Sales Analysis project combines an objective, fictional data, guided tasks and a ready-to-use SQL environment.