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JOIN with a Filter
Merchandising wants the electronics orders only, with the customer attached to each one.
Join orders to customers and show name, membership, product, total for orders where category is 'Electronics'. Order by total descending, then order_id.
The new idea: once two tables are joined, WHERE can filter on either one of them. You joined on customers but filtered on an orders column, and SQL doesn't care which side a column came from — after the join it's all one row. Table aliases (o, c) are what keep that readable once column names start repeating.
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Schema
orders
| order_id | customer_id | product | category | quantity | price | total | order_date | country | status |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1 | Laptop Pro | Electronics | 1 | 1299.99 | 1299.99 | 2024-01-15 | USA | completed |
| 2 | 2 | Wireless Mouse | Electronics | 2 | 49.99 | 99.98 | 2024-01-16 | Canada | completed |
| 3 | 3 | Office Chair | Furniture | 1 | 349.99 | 349.99 | 2024-01-17 | USA | completed |
customers
| customer_id | name | signup_date | membership | total_orders | |
|---|---|---|---|---|---|
| 1 | John Smith | john.smith@email.com | 2023-01-15 | Gold | 15 |
| 2 | Emma Wilson | emma.wilson@email.com | 2023-03-20 | Silver | 8 |
| 3 | Michael Brown | michael.brown@email.com | 2023-02-10 | Gold | 12 |
Expected output: 23 rows, each with the customer's name and membership attached
Hint
SELECT, JOIN, WHERE, and open the hint there if you stall.Concepts
SELECT JOIN WHERE
Practise the topic: SQL practice questions · JOIN practice
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