SQL: Distinct Product Count Per Customer (COUNT DISTINCT)

EasyDatabases

Description

> This problem is paper-only - see explanation for the canonical SQL solution. Given `OrderItems(order_id, customer_id, product_id, qty)`, return how many **distinct products** each customer has bought. Sort by customer_id ascending. **For the auto-grader:** return `[{ customer_id, distinct_products }]`.

Example 1

Input: rows = [{order_id:1,customer_id:1,product_id:10,qty:1},{order_id:2,customer_id:1,product_id:10,qty:5},{order_id:3,customer_id:1,product_id:11,qty:1},{order_id:4,customer_id:2,product_id:10,qty:1}]

Output: [{customer_id:1,distinct_products:2},{customer_id:2,distinct_products:1}]

Constraints

- 0 <= rows.length <= 10^4

Loading editor...