Market Basket Analysis - Most Frequently Co-Purchased Products
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Market Basket Analysis - Most Frequently Co-Purchased Products
You are given a Purchases table where each row represents one product in one order. Multiple products can appear in the same order. Write a SQL query to find all pairs of products that were purchased together in the same order, and count how many times each pair appeared. Only report pairs where product_1 < product_2 (lexicographic order) to avoid duplicates. Return product_1, product_2, and times_bought_together, ordered by times_bought_together descending, then product_1, then product_2. Table: Purchases
| Column Name | Type | Description |
|---|---|---|
| order_id | INT | ID of the order |
| product | VARCHAR | Name or ID of the product |
Examples
A+B appear in orders 1,2,4 (3 times). A+C appear in orders 1,4,5 (3 times). B+C appear in orders 1,3,4 (3 times).
Approach hint
Start with a simple approach, explain the trade-off, then move toward a cleaner or more scalable solution.
Common mistake
Skipping assumptions, edge cases, or trade-offs can make an otherwise good answer feel incomplete.