mysql基础常用命令

Posted 2021-01-09 致敬未来的自己

数据库

1查询 

Select * From table

select host,user,password from mysql.user where user=‘ybb‘ and host=‘%‘; 查询用户

select user,host,password from mysql.user;（查看用户，IP，密码对应表）
select user,host,db from mysql.db;(查看用户，IP，数据库对应表)
select distinct user from mysql.user;（查看所有用户）

 

2删除
truncate + 表名 删数据柳表结构

delete from t_learner  

3事务运行命令
/opt/server/mysql/bin/mysql
begin
commit

4修改root密码

方法1
mysql -hlocalhost -uroot -p

mysql>update mysql.user set password=password(‘新密码‘) where User="root"andHost="localhost";

方法2：用mysqladmin 

格式：mysqladmin -u用户名 -p旧密码 password 新密码 
例子：mysqladmin -uroot -p123456 password 123

5赋权

grant select,insert,update,delete,create on wlc.*  to [email protected] identified by ‘wlc123‘; 赋权增删改查

grant all privileges on wlcpay.* to [email protected]"%" identified by ‘wlcpay123‘;  赋权所有权限

flush privileges; 刷新权限列表
show grants for authuser; 查看用户权限

6添加索引

1）.添加PRIMARY KEY（主键索引）
mysql>ALTER TABLE `table_name` ADD PRIMARY KEY ( `column` )
2).添加UNIQUE(唯一索引)
mysql>ALTER TABLE `table_name` ADD UNIQUE (
`column`
)
3)添加INDEX(普通索引)
CREATE INDEX idx_tlearner_learnerUserID ON vocedudb.t_learner(LearnerUserID);
mysql>ALTER TABLE `table_name` ADD INDEX index_name ( `column` )
4).添加FULLTEXT(全文索引)
mysql>ALTER TABLE `table_name` ADD FULLTEXT ( `column`)
5).添加多列索引
mysql>ALTER TABLE `table_name` ADD INDEX index_name ( `column1`, `column2`, `column3` )

 

7 查看MYSQL数据库中所有用户
mysql> SELECT DISTINCT CONCAT(‘User: ‘‘‘,user,‘‘‘@‘‘‘,host,‘‘‘;‘) AS query FROM mysql.user;

查看数据库中具体某个用户的权限
mysql> show grants for ‘cactiuser‘@‘%‘;

备份数据库里表 mysqldump -hip  oil_statistics wl_daily_email -uwanglibao_yunwei -p > wl_daily_email2017.11.9
恢复
mysql -hhost -uroot -p user<user_back.sql

8 查看指定数据库的表的大小，
mysql> SELECT CONCAT(ROUND(SUM(DATA_LENGTH/1024/1024),2),‘MB‘) AS DATA FROM information_schema.TABLES WHERE table_schema=‘mysql‘ and table_name=‘user‘;