MySql015——使用子查询
一、创建customers表
########################
# Create customers table
########################
use `study`;
CREATE TABLE customers
(
cust_id int NOT NULL AUTO_INCREMENT,
cust_name char(50) NOT NULL ,
cust_address char(50) NULL ,
cust_city char(50) NULL ,
cust_state char(5) NULL ,
cust_zip char(10) NULL ,
cust_country char(50) NULL ,
cust_contact char(50) NULL ,
cust_email char(255) NULL ,
PRIMARY KEY (cust_id)
) ENGINE=InnoDB;
##########################
# Populate customers table
##########################
INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact, cust_email)
VALUES(10001, 'Coyote Inc.', '200 Maple Lane', 'Detroit', 'MI', '44444', 'USA', 'Y Lee', '[email protected]');
INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact)
VALUES(10002, 'Mouse House', '333 Fromage Lane', 'Columbus', 'OH', '43333', 'USA', 'Jerry Mouse');
INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact, cust_email)
VALUES(10003, 'Wascals', '1 Sunny Place', 'Muncie', 'IN', '42222', 'USA', 'Jim Jones', '[email protected]');
INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact, cust_email)
VALUES(10004, 'Yosemite Place', '829 Riverside Drive', 'Phoenix', 'AZ', '88888', 'USA', 'Y Sam', '[email protected]');
INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact)
VALUES(10005, 'E Fudd', '4545 53rd Street', 'Chicago', 'IL', '54545', 'USA', 'E Fudd');
二、子查询举例
2.1、使用的表格数据信息
customers表存储：客户信息
orders表存储：订单
orderitems表存储：订单中的详细信息
2.2、例子：要列出订购物品TNT2的所有客户
(1) 检索包含物品TNT2的所有订单的编号。
(2) 检索具有前一步骤列出的订单编号的所有客户的ID。
(3) 检索前一步骤返回的所有客户ID的客户信息。
-- (3) 检索前一步骤返回的所有客户ID的客户信息。
SELECT
cust_name, cust_contact
FROM
customers
WHERE
cust_id IN (
-- (2) 检索具有前一步骤列出的订单编号的所有客户的ID。
SELECT
cust_id
FROM
orders
WHERE
order_num IN (
-- (1) 检索包含物品TNT2的所有订单的编号。
SELECT
order_num
FROM
orderitems
WHERE
prod_id = 'TNT2'));
三、子查询特点
在SELECT语句中，子查询总是从内向外处理。