Practice / window functions
An online shop wants each customer's most recent order, labelled with their name.
orders
customers
Each customer's orders are on distinct dates, so "most recent" is unambiguous.
Your task: keep the latest order per customer_id (by order_date), join to customers, and return name, order_id, and order_date.
Assign your answer DataFrame to result. Row order doesn't matter.
ordersinput DataFrame| column | type |
|---|---|
| order_id | long |
| customer_id | long |
| order_date | string |
| order_id | customer_id | order_date |
|---|---|---|
| 1 | 100 | 2026-06-01 |
| 2 | 100 | 2026-06-09 |
| 3 | 101 | 2026-06-05 |
| 4 | 102 | 2026-06-02 |
| 5 | 102 | 2026-06-07 |
customersinput DataFrame| column | type |
|---|---|
| customer_id | long |
| name | string |
| customer_id | name |
|---|---|
| 100 | Priya |
| 101 | Sam |
| 102 | Wen |
nameorder_idorder_date· 3 rowsrow_number() partitioned by customer_id, ordered by order_date descending;
keep rn == 1 to get each customer's latest order, then join customers for the
name.
This problem builds on Window Functions (~9 min). Pop it open in a new tab if you want a quick recap.