The Relationship Detective
Three tables that do not talk to each other. Your job: wire them together with joins and answer the questions no single table can.
What you'll be able to build
Three tables that do not talk to each other. Your job: wire them together with joins and answer the questions no single table can. Along the way you pick up real, transferable SQL skills, not just this one project:
- Primary/foreign-key thinking and table relationships
- INNER JOIN to combine related rows
- LEFT JOIN to keep unmatched rows (and find the gaps)
- Multi-table joins (3+ tables) with qualified column names
- Self-joins to relate a table to itself
- Anti-joins (LEFT JOIN ... WHERE x IS NULL) to find orphans
A course like this one
Yours is built from your own placement, so module count and depth will differ. This map shows what a beginner-level SQL learner building The Relationship Detective actually gets.
- Module 1: Tables, Rows, and Query Intent6 lessons
Builds the table model for your the relationship detective.
- Module 2: Joins, Groups, and Data Shape6 lessons
Builds the join shape workflow for your the relationship detective.
- Module 3: Filters, Conditions, and Result Sets6 lessons
Builds the filter rule that powers your the relationship detective.
- Module 4: Reusable Query Patterns6 lessons
Builds the reusable query helper for your the relationship detective.
- Module 5: Transactions and Data Boundaries6 lessons
Builds the transaction boundary for your the relationship detective.
- Module 6: Reliable Reporting Queries3 lessons
Builds the report query for your the relationship detective.
How the lessons actually work
Every lesson has you predict what a piece of SQL code will output before you run it, then run it for real in your browser and fix what you got wrong. Each module ends in a challenge gate with hidden tests, so you can't advance until your code actually works. The course closes with a capstone that assembles everything into The Relationship Detective, and a runnable proof page tied to your own code.
Common questions
How long does the The Relationship Detective course take?
about 8.5 hours, across 6 modules and 33 lessons, at roughly 15 minutes per lesson. Your own course may run shorter or longer, since it's sized to your placement result, not a fixed template.
Do I need experience?
No. This is a beginner-tier SQL project, built for someone writing their first real SQL programs.
How much does it cost?
$15 one-time, no subscription. The first module is free, so you can see exactly how the course teaches before you pay for the rest.
No subscription. Module one is free.