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一、插入数据INSERT
1.插入完整数据（顺序插入） 语法一：
INSERT INTO 表名(字段1, 字段2, 字段3…字段n) VALUES(值1, 值2, 值3…值n);
语法二：
INSERT INTO 表名 VALUES(值1, 值2, 值3…值n);
2.指定字段插入数据
语法：
INSERT INTO 表名(字段1, 字段2, 字段3…) VALUES(值1, 值2, 值3…);
3.插入多条记录
语法：
INSERT INTO 表名 VALUES
(值1, 值2, 值3…值n),
(值1, 值2, 值3…值n),
(值1, 值2, 值3…值n);
4.插入查询结果
语法：
INSERT INTO 表名(字段1, 字段2, 字段3…字段n)
SELECT(字段1, 字段2, 字段3…字段n) FROM 表2
WHERE …;
二、更新数据UPDATE
语法：
UPDATE 表名 SET
字段1=值1,
字段2=值2,
WHERE CONDITION;
示例：
UPDATE mysql.user SET password=password(‘123’) where user=’root’ and host=’localhost’;
三、删除数据DELETE
语法：
DELETE FROM 表名
WHERE CONITION;
示例：
DELETE FROM mysql.user
WHERE password=’’;
四、权限管理
#创建用户
create user 'egon'@'1.1.1.1'>
create user 'egon'@'192.168.1.%'>
create user 'egon'@'%'> #授权：对文件夹，对文件，对文件某一字段的权限
查看帮助：help grant
常用权限有：select,update,alter,delete
all可以代表除了grant之外的所有权限
#针对所有库的授权:*.*
grant select on *.* to 'li'@'localhost' identified by '123'; #只在user表中可以查到li用户的select权限被设置为Y
#针对某一数据库：db1.*
grant select on db1.* to 'wang'@'%' identified by '123'; #只在db表中可以查到wang用户的select权限被设置为Y
#针对某一个表：db1.t1
grant select on db1.t1 to 'tom'@'%' identified by '123'; #只在tables_priv表中可以查到tom用户的select权限
#针对某一个字段：
mysql> select * from t3;
+------+-------+------+
| id | name | age |
+------+-------+------+
| 1 | egon1 | 18 |
| 2 | egon2 | 19 |
| 3 | egon3 | 29 |
+------+-------+------+
grant select (id,name),update (age) on db1.t3 to 'egon4'@'localhost' identified by '123';
#可以在tables_priv和columns_priv中看到相应的权限
mysql> select * from tables_priv where user='egon4'\G
mysql> select * from columns_priv where user='egon4'\G
#删除权限
revoke select on db1.* to 'alex'@'%';
五、mysql单表查询
1、单表查询的语法
SELECT 字段1,字段2... FROM 表名
WHERE 条件
GROUP BY field
HAVING 筛选
ORDER BY field
LIMIT 限制条数
2、关键字的执行优先级
from #找到表
where #拿着where指定的约束条件，去文件/表中取出一条条记录
group by #将取出的一条条记录进行分组group by，如果没有group by，则整体作为一组
having #将分组的结果进行having过滤
select #执行select
distinct #去重
order by #将结果按条件排序
limit #限制结果的显示条数
3、简单查询
#创建表
create database company;
use company;
create table employee(
id int not null unique auto_increment,
name varchar(20) not null,
sex enum('male','female') not null default 'male',
age int(3) unsigned not null default 28,
hire_date date not null,
post varchar(50),
post_comment varchar(100),
salary double(15,2),
office int,
depart_id int
);
#插入记录三个部门：教学，销售，运营
insert into employee(name,sex,age,hire_date,post,salary,office,depart_id) values
('wang','male',18,'20170301','teacher',7300.33,401,1),
('li','male',78,'20150302','teacher',1000000.31,401,1),
('jim','male',81,'20130305','teacher',8300,401,1),
('zhao','male',73,'20140701','teacher',3500,401,1),
('liwenzhou','male',28,'20121101','teacher',2100,401,1),
('jingliyang','female',18,'20110211','teacher',9000,401,1),
('jinxin','male',18,'19000301','teacher',30000,401,1),
('成龙','male',48,'20101111','teacher',10000,401,1),
('歪歪','female',48,'20150311','sale',3000.13,402,2),
('丫丫','female',38,'20101101','sale',2000.35,402,2),
('丁丁','female',18,'20110312','sale',1000.37,402,2),
('星星','female',18,'20160513','sale',3000.29,402,2),
('格格','female',28,'20170127','sale',4000.33,402,2),
('张野','male',28,'20160311','operation',10000.13,403,3),
('程咬金','male',18,'19970312','operation',20000,403,3),
('程咬银','female',18,'20130311','operation',19000,403,3),
('程咬铜','male',18,'20150411','operation',18000,403,3),
('程咬铁','female',18,'20140512','operation',17000,403,3)
;
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
| id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
| 1 | wang | male | 18 | 2017-03-01 | teacher | NULL | 7300.33 | 401 | 1 |
| 2 | li | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 |
| 3 | jim | male | 81 | 2013-03-05 | teacher | NULL | 8300.00 | 401 | 1 |
| 4 | zhao | male | 73 | 2014-07-01 | teacher | NULL | 3500.00 | 401 | 1 |
| 5 | liwenzhou | male | 28 | 2012-11-01 | teacher | NULL | 2100.00 | 401 | 1 |
| 6 | jingliyang | female | 18 | 2011-02-11 | teacher | NULL | 9000.00 | 401 | 1 |
| 7 | jinxin | male | 18 | 1900-03-01 | teacher | NULL | 30000.00 | 401 | 1 |
| 8 | 成龙 | male | 48 | 2010-11-11 | teacher | NULL | 10000.00 | 401 | 1 |
| 9 | 歪歪 | female | 48 | 2015-03-11 | sale | NULL | 3000.13 | 402 | 2 |
| 10 | 丫丫 | female | 38 | 2010-11-01 | sale | NULL | 2000.35 | 402 | 2 |
| 11 | 丁丁 | female | 18 | 2011-03-12 | sale | NULL | 1000.37 | 402 | 2 |
| 12 | 星星 | female | 18 | 2016-05-13 | sale | NULL | 3000.29 | 402 | 2 |
| 13 | 格格 | female | 28 | 2017-01-27 | sale | NULL | 4000.33 | 402 | 2 |
| 14 | 张野 | male | 28 | 2016-03-11 | operation | NULL | 10000.13 | 403 | 3 |
| 15 | 程咬金 | male | 18 | 1997-03-12 | operation | NULL | 20000.00 | 403 | 3 |
| 16 | 程咬银 | female | 18 | 2013-03-11 | operation | NULL | 19000.00 | 403 | 3 |
| 17 | 程咬铜 | male | 18 | 2015-04-11 | operation | NULL | 18000.00 | 403 | 3 |
| 18 | 程咬铁 | female | 18 | 2014-05-12 | operation | NULL | 17000.00 | 403 | 3 |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
# 简单查询
SELECT id, name, sex, age, hire_date, post, post_comment, salary, office, depart_id FROM employee;
SELECT * FROM employee;
SELECT name, salary FROM employee;
# 避免重复DISTINCT
SELECT DISTINCT post FROM employee;
+-----------+
| post |
+-----------+
| teacher |
| sale |
| operation |
+-----------+
# 通过四则运算查询
SELECT name, salary * 12 FROM employee;
SELECT name, salary * 12 AS Annual_salary FROM employee;
SELECT name, salary * 12 Annual_salary FROM employee;
+------------+---------------+
| name | Annual_salary |
+------------+---------------+
| wang | 87603.96 |
| li | 12000003.72 |
| jim | 99600.00 |
| zhao | 42000.00 |
| liwenzhou | 25200.00 |
| jingliyang | 108000.00 |
| jinxin | 360000.00 |
| 成龙 | 120000.00 |
| 歪歪 | 36001.56 |
| 丫丫 | 24004.20 |
| 丁丁 | 12004.44 |
| 星星 | 36003.48 |
| 格格 | 48003.96 |
| 张野 | 120001.56 |
| 程咬金 | 240000.00 |
| 程咬银 | 228000.00 |
| 程咬铜 | 216000.00 |
| 程咬铁 | 204000.00 |
+------------+---------------+
# 定义显示格式
CONCAT() 函数用于连接字符串
SELECT CONCAT('姓名: ', name, ' 年薪: ', salary * 12) AS Annual_salary FROM employee;
CONCAT_WS() 第一个参数为分隔符
SELECT CONCAT_WS(':', name, salary * 12) AS Annual_salary FROM employee;
+----------------------+
| Annual_salary |
+----------------------+
| wang:87603.96 |
| li:12000003.72 |
| jim:99600.00 |
| zhao:42000.00 |
| liwenzhou:25200.00 |
| jingliyang:108000.00 |
| jinxin:360000.00 |
| 成龙:120000.00 |
| 歪歪:36001.56 |
| 丫丫:24004.20 |
| 丁丁:12004.44 |
| 星星:36003.48 |
| 格格:48003.96 |
| 张野:120001.56 |
| 程咬金:240000.00 |
| 程咬银:228000.00 |
| 程咬铜:216000.00 |
| 程咬铁:204000.00 |
+----------------------+
练习： （1）查出所有员工的名字，薪资,格式为
（2）查出所有的岗位（去掉重复）
（3）查出所有员工名字，以及他们的年薪,年薪的字段名为annual_year
select concat(' ','') from employee;
select distinct depart_id from employee;
select name,salary*12 annual_salary from employee;
4、WHERE约束
# 1:单条件查询
SELECT name FROM employee WHERE post = 'sale';
# 2:多条件查询
SELECT name, salary FROM employee WHERE post = 'teacher' AND salary > 10000;
# 3:关键字BETWEEN AND
SELECT name, salary FROM employee WHERE salary BETWEEN 10000 AND 20000;
SELECT name, salary FROM employee WHERE salary NOT BETWEEN 10000 AND 20000;
# 4:关键字IS NULL(判断某个字段是否为NULL不能用等号，需要用IS)
SELECT name, post_comment FROM employee WHERE post_comment IS NULL;
SELECT name, post_comment FROM employee WHERE post_comment IS NOT NULL;
SELECT name, post_comment FROM employee WHERE post_comment = ''; #注意''是空字符串，不是null
ps：
执行
update employee set post_comment = '' where id = 2;
再用上条查看，就会有结果了
# 5:关键字IN集合查询
SELECT name, salary FROM employee WHERE salary = 3000 OR salary = 3500 OR salary = 4000 OR salary = 9000;
SELECT name, salary FROM employee WHERE salary IN(3000, 3500, 4000, 9000);
SELECT name, salary FROM employee WHERE salary NOT IN(3000, 3500, 4000, 9000);
# 6:关键字LIKE模糊查询
通配符’ % ’
SELECT * FROM employee WHERE name LIKE 'eg%';
通配符’_’
SELECT * FROM employee WHERE name LIKE 'al__';
练习：
（1）查看岗位是teacher的员工姓名、年龄
（2）查看岗位是teacher且年龄大于30岁的员工姓名、年龄
（3）查看岗位是teacher且薪资在9000-1000范围内的员工姓名、年龄、薪资
（4）查看岗位描述不为NULL的员工信息
（5）查看岗位是teacher且薪资是10000或9000或30000的员工姓名、年龄、薪资
（6）查看岗位是teacher且薪资不是10000或9000或30000的员工姓名、年龄、薪资
（7）查看岗位是teacher且名字是jin开头的员工姓名、年薪
select name,age from employee where post = 'teacher';
select name,age from employee where post='teacher' and age > 30;
select name,age,salary from employee where post='teacher' and salary between 9000 and 10000;
select * from employee where post_comment is not null;
select name,age,salary from employee where post='teacher' and salary in (10000,9000,30000);
select name,age,salary from employee where post='teacher' and salary not in (10000,9000,30000);
select name,salary*12 from employee where post='teacher' and name like 'jin%';
mysql> select name,salary*12 as year_salary from employee where post='teacher' and name like 'jin%';
5、分组查询:GROUP BY
（1）GROUP BY
单独使用GROUP BY关键字分组
SELECT post FROM employee GROUP BY post;
注意：我们按照post字段分组，那么select查询的字段只能是post，想要获取组内的其他相关信息，需要借助函数
GROUP BY关键字和GROUP_CONCAT()函数一起使用
SELECT post,GROUP_CONCAT(name) FROM employee GROUP BY post; #按照岗位分组，并查看组内成员名
SELECT post,GROUP_CONCAT(name) as emp_members FROM employee GROUP BY post;
GROUP BY与聚合函数一起使用
select post,count(id) as count from employee group by post; #按照岗位分组，并查看每个组有多少人
如果我们用unique的字段作为分组的依据，则每一条记录自成一组，这种分组没有意义
多条记录之间的某个字段值相同，该字段通常用来作为分组的依据
（2）聚合函数
#强调：聚合函数聚合的是组的内容，若是没有分组，则默认一组
示例：
SELECT COUNT(*) FROM employee;
SELECT COUNT(*) FROM employee WHERE depart_id=1;
SELECT MAX(salary) FROM employee;
SELECT MIN(salary) FROM employee;
SELECT AVG(salary) FROM employee;
SELECT SUM(salary) FROM employee;
SELECT SUM(salary) FROM employee WHERE depart_id=3;
练习：
（1）查询岗位名以及岗位包含的所有员工名字
（2）查询岗位名以及各岗位内包含的员工个数
（3）查询公司内男员工和女员工的个数
（4）查询岗位名以及各岗位的平均薪资
（5）查询岗位名以及各岗位的最高薪资
（6）查询岗位名以及各岗位的最低薪资
（7）查询男员工与男员工的平均薪资，女员工与女员工的平均薪资
mysql> select post,group_concat(name) from employee group by post;
mysql> select post,count(id) from employee group by post;
mysql> select sex,count(id) from employee group by sex;
mysql> select post,avg(salary) from employee group by post;
mysql> select post,max(salary) from employee group by post;
mysql> select post,min(salary) from employee group by post;
mysql> select sex,avg(salary) from employee group by sex;
6、HAVING过滤
HAVING与WHERE不一样的地方在于!!!!!!
#！！！执行优先级从高到低：where > group by > having
#1. Where 发生在分组group by之前，因而Where中可以有任意字段，但是绝对不能使用聚合函数。
#2. Having发生在分组group by之后，因而Having中可以使用分组的字段，无法直接取到其他字段,可以使用聚合函数
练习：
1. 查询各岗位内包含的员工个数小于2的岗位名、岗位内包含员工名字、个数
2. 查询各岗位平均薪资大于10000的岗位名、平均工资
3. 查询各岗位平均薪资大于10000且小于20000的岗位名、平均工资
mysql> select post,group_concat(name),count(id) from employee group by post having count(id) < 2;
mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000;
mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 and avg(salary) select * from employee ORDER BY age asc,hire_date desc;
mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 order by avg(salary) asc;
mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 order by avg(salary) desc;
8、限制查询的记录数:LIMIT
SELECT * FROM employee ORDER BY salary DESC LIMIT 3; # 默认初始位置为0
SELECT * FROM employee ORDER BY salary DESC LIMIT 0, 5; # 从第0开始，即先查询出第一条，然后包含这一条在内往后查5条
SELECT * FROM employee ORDER BY salary DESC LIMIT 5, 5; # 从第5开始，即先查询出第6条，然后包含这一条在内往后查5条
练习：分页显示，每页5条
mysql> select * from employee limit 0,5; #显示第1到5条记录
mysql> select * from employee limit 5,5; #显示第5到10条记录
mysql> select * from employee limit 10,5; #显示第10到15条记录
9、使用正则表达式查询
SELECT * FROM employee WHERE name REGEXP '^ale';
SELECT * FROM employee WHERE name REGEXP 'on$';
SELECT * FROM employee WHERE name REGEXP 'm{2}';
小结：对字符串匹配的方式
WHERE name = 'li';
WHERE name LIKE 'yua%';
WHERE name REGEXP 'on$';
练习：
查看所有员工中名字是jin开头，n或者g结果的员工信息
select * from employee where name regexp '^jin.*[gn]$';
六、mysql多表查询
1、建表
create table department(id int,name varchar(20));
create table employee(
id int primary key auto_increment,
name varchar(20),
sex enum('male','female') not null default 'male',
age int,
dep_id int
);
#插入数据
insert into department values(200,'技术'),(201,'人力资源'),(202,'销售'),(203,'运营');
insert into employee(name,sex,age,dep_id) values
('egon','male',18,200),
('alex','female',48,201),
('wupeiqi','male',38,201),
('yuanhao','female',28,202),
('liwenzhou','male',18,200),
('jingliyang','female',18,204)
;
2、多表连接查询
（1）交叉连接：不适用任何匹配条件。生成笛卡尔积
mysql> select * from department;
+------+--------------+
| id | name |
+------+--------------+
| 200 | 技术 |
| 201 | 人力资源 |
| 202 | 销售 |
| 203 | 运营 |
+------+--------------+
mysql> select * from employee;
+----+------------+--------+------+--------+
| id | name | sex | age | dep_id |
+----+------------+--------+------+--------+
| 1 | egon | male | 18 | 200 |
| 2 | alex | female | 48 | 201 |
| 3 | wupeiqi | male | 38 | 201 |
| 4 | yuanhao | female | 28 | 202 |
| 5 | liwenzhou | male | 18 | 200 |
| 6 | jingliyang | female | 18 | 204 |
+----+------------+--------+------+--------+
mysql> select * from employee,department;
（2）内连接：只连接匹配的行
#找两张表共有的部分，相当于利用条件从笛卡尔积结果中筛选出了正确的结果
#department没有204这个部门，因而employee表中关于204这条员工信息没有匹配出来
mysql> select employee.id,employee.name,employee.age,employee.sex,department.name from employee inner join department on employee.dep_id=department.id;
+----+-----------+------+--------+--------------+
| id | name | age | sex | name |
+----+-----------+------+--------+--------------+
| 1 | egon | 18 | male | 技术 |
| 2 | alex | 48 | female | 人力资源 |
| 3 | wupeiqi | 38 | male | 人力资源 |
| 4 | yuanhao | 28 | female | 销售 |
| 5 | liwenzhou | 18 | male | 技术 |
+----+-----------+------+--------+--------------+
mysql> select employee.id,employee.name,employee.age,employee.sex,department.name from employee,department where employee.dep_id=department.id;
（3）外链接之左连接：优先显示左表全部记录
#以左表为准，即找出所有员工信息，当然包括没有部门的员工
#本质就是：在内连接的基础上增加左边有右边没有的结果
mysql> select employee.id,employee.name,department.name as depart_name from employee left join department on employee.dep_id=department.id;
+----+------------+--------------+
| id | name | depart_name |
+----+------------+--------------+
| 1 | egon | 技术 |
| 5 | liwenzhou | 技术 |
| 2 | alex | 人力资源 |
| 3 | wupeiqi | 人力资源 |
| 4 | yuanhao | 销售 |
| 6 | jingliyang | NULL |
+----+------------+--------------+
（4）外链接之右连接：优先显示右表全部记录
#以右表为准，即找出所有部门信息，包括没有员工的部门
#本质就是：在内连接的基础上增加右边有左边没有的结果
mysql> select employee.id,employee.name,department.name as depart_name from employee right join department on employee.dep_id=department.id;
+------+-----------+--------------+
| id | name | depart_name |
+------+-----------+--------------+
| 1 | egon | 技术 |
| 2 | alex | 人力资源 |
| 3 | wupeiqi | 人力资源 |
| 4 | yuanhao | 销售 |
| 5 | liwenzhou | 技术 |
| NULL | NULL | 运营 |
+------+-----------+--------------+
（5）全外连接：显示左右两个表全部记录
全外连接：在内连接的基础上增加左边有右边没有的和右边有左边没有的结果
#注意：mysql不支持全外连接 full JOIN
#强调：mysql可以使用此种方式间接实现全外连接
select * from employee left join department on employee.dep_id = department.id
union
select * from employee right join department on employee.dep_id = department.id
;
+------+------------+--------+------+--------+------+--------------+
| id | name | sex | age | dep_id | id | name |
+------+------------+--------+------+--------+------+--------------+
| 1 | egon | male | 18 | 200 | 200 | 技术 |
| 5 | liwenzhou | male | 18 | 200 | 200 | 技术 |
| 2 | alex | female | 48 | 201 | 201 | 人力资源 |
| 3 | wupeiqi | male | 38 | 201 | 201 | 人力资源 |
| 4 | yuanhao | female | 28 | 202 | 202 | 销售 |
| 6 | jingliyang | female | 18 | 204 | NULL | NULL |
| NULL | NULL | NULL | NULL | NULL | 203 | 运营 |
+------+------------+--------+------+--------+------+--------------+
#注意 union与union all的区别：union会去掉相同的纪录
3、符合条件连接查询
#示例1：以内连接的方式查询employee和department表，并且employee表中的age字段值必须大于25,即找出年龄大于25岁的员工以及员工所在的部门
select employee.name,department.name from employee inner join department on employee.dep_id = department.id where age > 25;
+---------+--------------+
| name | name |
+---------+--------------+
| alex | 人力资源 |
| wupeiqi | 人力资源 |
| yuanhao | 销售 |
+---------+--------------+
#示例2：以内连接的方式查询employee和department表，并且以age字段的升序方式显示
select employee.id,employee.name,employee.age,department.name from employee,department where employee.dep_id = department.id and age > 25 order by age asc;
+----+---------+------+--------------+
| id | name | age | name |
+----+---------+------+--------------+
| 4 | yuanhao | 28 | 销售 |
| 3 | wupeiqi | 38 | 人力资源 |
| 2 | alex | 48 | 人力资源 |
+----+---------+------+--------------+
4、子查询
#1：子查询是将一个查询语句嵌套在另一个查询语句中。
#2：内层查询语句的查询结果，可以为外层查询语句提供查询条件。
#3：子查询中可以包含：IN、NOT IN、ANY、ALL、EXISTS 和 NOT EXISTS等关键字
#4：还可以包含比较运算符：= 、 !=、> 、 25);
#查看技术部员工姓名
select name from employee where dep_id in (select id from department where name='技术');
#查看不足1人的部门名(子查询得到的是有人的部门id)
select name from department where id not in (select distinct dep_id from employee);
（2）带比较运算符的子查询
#比较运算符：=、!=、>、>=、 (select avg(age) from emp);
#查询大于部门内平均年龄的员工名、年龄
select t1.name,t1.age from emp t1
inner join
(select dep_id,avg(age) avg_age from emp group by dep_id) t2 on t1.dep_id = t2.dep_id where t1.age > t2.avg_age;
（3）带EXISTS关键字的子查询
EXISTS关字键字表示存在。在使用EXISTS关键字时，内层查询语句不返回查询的记录。
而是返回一个真假值。True或False
当返回True时，外层查询语句将进行查询；当返回值为False时，外层查询语句不进行查询
#department表中存在dept_id=203，Ture
mysql> select * from employee where exists (select id from department where id=200);
#department表中存在dept_id=205，False
mysql> select * from employee where exists (select id from department where id=204);
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