MySQL基本命令

centos7从外部无法连接，iptables无限制。
http://stackoverflow.com/questions/16161889/cant-connect-to-remote-mysql-server-with-error-61

sudo firewall-cmd --zone=public --permanent --add-service=mysql
sudo systemctl restart firewalld

查看用户

select Host,User,Password from mysql.user; 

SHOW 指令(‘[..]'里的可选)

show databases; #显示mysql中所有数据库的名称
show tables [ from db_name] #显示mysql中的相关表
show full fields from tbl_name  #列出表字段完整属性
show columns from table_name [ from database_name ] ; 或show columns from database_name.table_name; #显示表中列名称
show grants for user_name;  #显示一个用户的权限，显示结果类似于grant 命令
show index from tbl_name #列出表索引
show index from table_name #显示表的索引

添加用户

CREATE USER 'john'@'192.168.189.71' IDENTIFIED BY "123";
grant all privileges on *.* to joe@localhost identified by '1';
flush privileges;

mysql移动到别的目录下

vim /etc/my.cnf

修改列名表名

alter table test rename test1; --修改表名 
alter table test add  column name varchar(10); --添加表列  
alter table test drop  column name; --删除表列 
alter table test modify address char(10) --修改表列类型  
alter table test change address address  char(40) 
alter table test change  column address address1 varchar(30)--修改表列名    

为什么不能不带类型的修改表名简直不合理！

视图

create view 视图名称[(column_list)] as select语句
create view  province_view as select * from province;
select * from province_view;

类型转换

inet_ntoa(sa) 将int型ip转换为字符
时间转换

去重