Write a PostgreSQL query to find the top three customers by total spend in the last completed quarter by joining customers and transactions. Return customer_id, customer_name, and total_spend, ordered by highest spend first. Assume CURRENT_DATE = '2024-08-15', so the target quarter is 2024-04-01 to 2024-06-30.
| Column | Type | Description |
|---|---|---|
| customer_id INT PK | ||
| customer_name VARCHAR(100) | ||
| segment VARCHAR(50) | ||
| onboarded_at DATE |
| Column | Type | Description |
|---|---|---|
| transaction_id INT PK | ||
| customer_id INT FK | ||
| transaction_date DATE | ||
| amount DECIMAL(10,2) | ||
| cost_center VARCHAR(50) |
| 101 | Acme Health | Enterprise | 2023-11-10 |
| 102 | BluePeak Retail | Mid-Market | 2024-01-05 |
| 104 | Delta Manufacturing | Enterprise | 2023-09-15 |
| 1002 | 101 | 2024-04-01 | 300.00 | SaaS |
| 1006 | 102 | 2024-05-18 | 1200.00 | SaaS |
| 1010 | 104 | 2024-06-25 | 1600.00 | Labor |