Что вернёт запрос?
```sql
SELECT
SUM(CASE WHEN status = 'paid' THEN amount ELSE 0 END) AS paid_total,
SUM(CASE WHEN status = 'refund' THEN amount ELSE 0 END) AS refund_total,
SUM(CASE WHEN status = 'paid' THEN amount ELSE 0 END) -
SUM(CASE WHEN status = 'refund' THEN amount ELSE 0 END) AS net_revenue
FROM orders;
```
Данные: (paid, 100), (paid, 200), (refund, 50), (cancelled, 75).
SQLhardsenior
Варианты ответа
paid_total = 300, refund_total = 50, net_revenue = 250. Строка cancelled получает 0 в обоих CASE и не влияет на суммы