# Mysql常用命令

## 数据定义语句(DDL)

### 数据库操作

- 登录数据库：mysql -uroot -proot
- 创建数据库：create database test
- 查看所有数据库：show databases
- 使用数据库：use test
- 查看所有数据表：show tables
- 删除数据库：drop database test

### 表操作

- 创建表：create table emp(ename varchar(10),hiredate date,sal decimal(10,2),deptno int(2))  
         create table dept(deptno int(2),deptname varchar(10))
- 查看表的定义：desc emp
- 查看表定义（详细）：show create table emp \G
- 删除表：drop table emp
- 修改表字段：alter table emp modify ename varchar(20)
- 添加表字段：alter table emp add column age int(3)
- 删除表字段：alter table emp drop column age
- 字段改名；alter table emp change age age1 int(4)
- 修改表名：alter table emp rename emp1

## 数据操纵语句(DML)

### 插入记录

- 指定名称插入：insert into emp (ename,hiredate,sal,deptno) values ('zhangsan','2018-01-01','2000',1)
- 不指定名称插入：insert into emp values ('lisi','2018-01-01','2000',1)
- 批量插入数据：insert into dept values(1,'dept1'),(2,'dept2')

### 修改记录

update emp set sal='4000',deptno=2 where ename='zhangsan'

### 删除记录

delete from emp where ename='zhangsan'

### 查询记录

- 查询所有记录：select * from emp
- 查询不重复的记录：select distinct deptno from emp
- 条件查询：select * from emp where deptno=1 and sal<3000
- 排序和限制：select * from emp order by deptno desc limit 2
- 聚合(查询部门人数大于1的部门编号)：select deptno,count(1) from emp group by deptno having count(1) > 1
- 连接查询：select * from emp e left join dept d on e.deptno=d.deptno
- 子查询：select * from emp where deptno in (select deptno from dept)
- 记录联合：select deptno from emp union select deptno from dept

## 数据控制语句(DCL)

- 授予操作权限：grant select,insert on test.* to 'test'@'localhost' identified by '123'
- 收回操作权限：revoke insert on test.* from 'test'@'localhost'

## 其他

### 字符集相关
- 查看字符集：show variables like 'character%'
- 创建数据库时指定字符集：create database test1 character set utf8

### 权限相关
- 授予所有数据库的所有权限：grant all privileges on *.* to z1@localhost identified by '123'
- 授予所有数据库的所有权限(包括grant)：grant all privileges on *.* to z1@localhost with grant option
- 授予SUPER PROCESS FILE权限：grant super,process,file on *.* to z3@localhost
- 只授予登录权限：grant usage on *.* to z4@localhost
- 查看账号权限：show grants for z1@localhost
- 修改自己的密码：set password = password('123')
- 管理员修改他人密码：set password for 'z1'@'localhost' = password('123')
- 删除账号：drop user z2@localhost