# mysql 常用操作

mysql 连接

使用 mysq l命令：`yum install mysql`

用法：

* -u ：指定用户
* -p ：指定密码
* -h ：指定主机
* -P ：指定端口
* -S ：指定连接的sock
* -e ：指定运行sql命令

```bash
mysql -uroot -p123456

mysql -uroot -p123456 -h127.0.0.1 -P3306

mysql -uroot -p123456 -S/tmp/mysql.sock

mysql -uroot -p123456 -e “show databases”
```

查看当前用户

```sql
> select user();
```

> select user()\G; \G 为按列显示

查看mysqlb版本

```sql
> select version();
```

> mysql结构 ： 库 --> 表 --> 行 --> 字段Aborted

查看当前使用的数据库

```sql
> select databsase();
```

查看数据库

```sql
> show databases;
```

查看数据库中的表

```bash
> use mysql;  # 切换库
> show tables; # 查看mysql库中的所有表
```

查看表结构

```sql
> desc tbname;
```

查看数据库和表的创建语句

```bash
> show create database dbname;
> show create table tbname;
```

查看数据库状态

```sql
> show status;
```

查看进程工作

```sql
> show processlist; 
> show full processlist;
```

查看各参数

```sql
> show variables; 
> show variables like 'max_connect%';
```

修改参数

```sql
> set global max_connect_errors=1000;
```

用户登陆授权

```sql
> grant dbcommand on dbname.tbname to 'user'@'host' identified by 'password';
> flush privileges;      #授权后刷新权限
```

查看用户权限

```sql
> show grants;
> show grants for user@192.168.127.1;
```


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