40 Subqueries
SELECT *
FROM products
WHERE unit_price >
(SELECT unit_price
FROM products
WHERE product_id = 3)
## 篩選價格比萵筍貴的物品
SELECT *
FROM employees
WHERE salary >
(SELECT AVG(salary)
FROM employees)
## 篩選員工工資比平均高的
41 The IN Operator
- 使用subqueries的syntax
SELECT *
FROM clients
WHERE client_id NOT IN
(SELECT DISTINCT client_id
FROM invoices)
## 找出沒有開發(fā)票的客戶