SQL Quest › SQL Interview Questions › Aggregation & Grouping
Daily Active Customers
Calculate daily active customers (DAC). For each order_date, show the order_date, the number of unique customers who placed orders (active_customers), and the total_orders on that day. Sort by order_date. DAU/DAC is a standard product-analytics metric.
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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 |
Expected output: order_date: 2024-01-05, active_customers: 2, total_orders: 3
Hint
Concepts
SELECT GROUP BY Aggregation COUNT DISTINCT GROUP BY + Date Functions
Practise the topic: SQL practice questions · GROUP BY exercises · Advanced SQL interview questions
Read the concept: SQL GROUP BY tutorial
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