@author:トービン
@date:2019年10月31日午後5時44分42秒
MySQL4.1の紹介は、サブクエリをサポート。
# 嵌套
SELECT cust_name, cust_contact
FROM customers
WHERE cust_id IN (SELECT cust_id
FROM orders
WHERE order_num IN (SELECT order_num
FROM orderitems
WHERE prod_id = 'TNT2'));
SELECT cust_name,
cust_state,
(SELECT COUNT(*)
FROM orders
WHERE orders.cust_id = customers.cust_id) AS orders
FROM customers
ORDER BY cust_name;