SQL邏輯查詢語句執行順序

傳送門

1. SQL邏輯查詢語句執行順序

2. MySQL聯接查詢操做

3. MySQL掃盲篇

4. MySQL存儲引擎介紹

5. MySQL數據類型和屬性

6. MySQL處理數據庫和表的經常使用命令

SELECT a.customer_id, COUNT(b.order_id) as total_orders

FROM table1 AS a

LEFT JOIN table2 AS b

ON a.customer_id = b.customer_id

WHERE a.city = 'hangzhou'

GROUP BY a.customer_id

HAVING count(b.order_id) < 2

ORDER BY total_orders DESC;