Recommendations: 'Also Bought'
Build the 'customers who bought X also bought Y' engine with self-joins and co-occurrence counts, real recommender logic in pure SQL.
What you'll be able to build
Build the 'customers who bought X also bought Y' engine with self-joins and co-occurrence counts, real recommender logic in pure SQL. Along the way you pick up real, transferable SQL skills, not just this one project:
- self-joining an orders table to itself
- pairing items within the same order
- COUNT co-occurrences and rank them
- excluding self-pairs and duplicates
- GROUP BY two columns
- top-N per item with a window/CTE
A course like this one
Yours is built from your own placement, so module count and depth will differ. This map shows what a intermediate-level SQL learner building Recommendations actually gets.
- Module 1: Tables, Rows, and Query Intent5 lessons
Builds the table model for your recommendations.
- Module 2: Joins, Groups, and Data Shape5 lessons
Builds the join shape workflow for your recommendations.
- Module 3: Filters, Conditions, and Result Sets5 lessons
Builds the filter rule that powers your recommendations.
- Module 4: Reusable Query Patterns5 lessons
Builds the reusable query helper for your recommendations.
- Module 5: Transactions and Data Boundaries5 lessons
Builds the transaction boundary for your recommendations.
- Module 6: Reliable Reporting Queries3 lessons
Builds the report query for your recommendations.
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 Recommendations, and a runnable proof page tied to your own code.
Common questions
How long does the Recommendations: 'Also Bought' course take?
about 7 hours, across 6 modules and 28 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?
Some. This is an intermediate-tier SQL project, so it assumes you're comfortable with SQL basics and pushes past them.
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.