SQL: Customers Who Placed Orders (INNER JOIN)

EasyDatabases

Description

> This problem is paper-only - see explanation for the canonical SQL solution. The auto-grader validates an in-memory simulation that produces the same result an INNER JOIN would. Given two tables: ``` Customers(id, name) Orders(id, customer_id, total) ``` Return the **distinct names of customers who have placed at least one order**, sorted alphabetically. **For the auto-grader:** implement `customersWithOrders(customers, orders)` where each list contains plain objects matching the schema. Return a sorted array of customer names.

Example 1

Input: customers = [{id:1,name:"Alice"},{id:2,name:"Bob"},{id:3,name:"Cleo"}], orders = [{id:10,customer_id:1,total:50},{id:11,customer_id:1,total:25},{id:12,customer_id:3,total:99}]

Output: ["Alice","Cleo"]

Explanation: Bob has no orders so he is excluded. Alice has two orders but appears only once.

Constraints

- 0 <= customers.length <= 10^4 - 0 <= orders.length <= 10^4 - Customer ids are unique. Some orders may reference missing customers (treat as no-match). - Names are unique per customer id.

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