CREATE TABLE publisher(
P_ID BIGINT(20) NOT NULL AUTO_INCREMENT PRIMARY KEY COMMENT '出版社编号',
P_NAME VARCHAR(20) UNIQUE NOT NULL COMMENT '出版社名',
P_LINKMAN VARCHAR(20) NOT NULL COMMENT '出版社联系人',
P_TEL VARCHAR(20) COMMENT '电话',
P_ADDRESS VARCHAR(50) COMMENT '地址'
)
CREATE TABLE book(
B_ID BIGINT(20) NOT NULL AUTO_INCREMENT PRIMARY KEY COMMENT '图书编号',
B_NAME VARCHAR(20) UNIQUE NOT NULL COMMENT '图书名',
P_ID BIGINT(20) COMMENT '出版社编号',
B_AUTHOR VARCHAR(20) COMMENT '图书作者',
B_PRICE FLOAT COMMENT '价格'
)
#查询出版社的所有信息
SELECT * FROM `publisher`
#查询B_NAME='计算机基础'的所有信息，包括出版社的信息
SELECT p.P_NAME,p.P_LINKMAN,b.B_NAME,b.B_PRICE,b.B_AUTHOR
FROM book b INNER JOIN `publisher` p ON b.P_ID=p.P_ID
WHERE b.B_NAME='计算机基础';
#查询所有清华大学出版社出版的所有书籍
SELECT p.P_NAME,p.P_LINKMAN,b.B_NAME,b.B_PRICE,b.B_AUTHOR
FROM book b INNER JOIN `publisher` p ON b.P_ID=p.P_ID
WHERE p.`P_NAME`='清华大学出版社';
#将出版社P_LINKMAN=王伟的手机号修改
UPDATE `publisher` SET P_TEL='11111111111' WHERE P_LINKMAN='王伟';
#查询book表中B_AUTHOR以王**开头的所有书籍
SELECT * FROM book WHERE B_AUTHOR='王五';
SELECT * FROM book WHERE B_AUTHOR LIKE '王%';
#查询book表中B_AUDHOR以 a 结尾的素有书籍
SELECT * FROM book WHERE B_NAME LIKE '%A';
#查询book表中B_AUDHOR包含 C 结尾的素有书籍
SELECT * FROM book WHERE B_NAME LIKE '%C%';
#内连接 inner join
SELECT 字段名1，字段名2，，，，字段n FROM 表1 别名1 INNER JOIN 表2 别名2 ON 条件 WHERE 条件
SELECT p.P_NAME,p.P_LINKMAN,b.B_NAME,b.B_PRICE,b.B_AUTHOR
FROM book b INNER JOIN `publisher` p ON b.P_ID=p.P_ID
#-------------------------外连接----------------------------
#左外连接:left join
#左连接当条件不满足的时候，以左边的表为主
SELECT p.P_NAME,p.P_LINKMAN,b.B_NAME,b.B_PRICE,b.B_AUTHOR
FROM book b LEFT JOIN `publisher` p ON b.P_ID=p.P_ID
#右外连接:right join
#右连接当条件不满足的时候，以右边的表为主
SELECT p.P_NAME,p.P_LINKMAN,b.B_NAME,b.B_PRICE,b.B_AUTHOR
FROM book b RIGHT JOIN `publisher` p ON b.P_ID=p.P_ID
#-------------------3表查询--------------------------------
#求出teacherId=4的平均得分
#得到总分数
SELECT SUM(score) AS total FROM `teacher_question` WHERE teacherId=3;
SELECT COUNT(*) AS num FROM `teacher_question`WHERE teacherId=3 AND questionId=3;
SELECT
temp1.total / temp2.num AS 平均分
FROM
(SELECT SUM(score) AS total FROM `teacher_question` WHERE teacherId = 3) temp1,
(SELECT COUNT(*) AS num FROM`teacher_question` WHERE teacherId = 3 AND questionId = 3) temp2
#需求：想知道1号顾客具体买了哪些商品（商品名，价格，客户名，手机号）
SELECT g.goodName,g.price,c.customerName,c.phone
FROM goods g INNER JOIN goods_customer gc INNER JOIN customer c
ON g.id = gc.goodId AND gc.customerId = c.id
WHERE c.customerName = '张三'