mysql查帮助手册的技巧：help 你的命令；比如 help create;
>>显示mysql中用户：select host,user from mysql.user;
>>>创建用户：mysql> create user 'zhangpeng'@'%' identified by 'oradt!@#&*(';
>>授权某个用户拥有某个数据库的任何权限：
GRANT ALL PRIVILEGES ON stock_info.* TO 'test'@'%' IDENTIFIED BY '123456' WITH GRANT OPTION;
创建数据库： mysql> create database stock_info default charset utf8 collate utf8_general_ci;
>>> 查看用户权限(显示用户权限): show grants from 用户名; //show grants; 显示当前自己的权限
修改用户密码-> 首先进入命令行下, 以root用户登录，命令：mysql -uroot -p 回车 输入密码再回车;
USER mysql;
UPADTE user set password=password('root') where user='root';
mysql> FLUSH PRIVILEGES;//记得要这句话
>>> mysql优化表(回收表占用的闲置数据库空间),代码如何：
REPAIR TABLE `table_name` 修复表
OPTIMIZE TABLE `table_name` 优化表
1.备份表结构(加上-d只备份表结构，不加此参数表结构、数据都备份)：
C:Program FilesMySQLMySQL Server 5.6in>mysqldump -hlocalhost -P3308 -uroot
-p -d stock_info>F:/stock_info.sql
Enter password: ******
备份单个表的数据(表必须不存在)：
create table st_pool_bak as SELECT id,code FROM `st_pool` ;
mysql 查看数据库中所有表的记录数(总记录数)use information_schema;
select table_name,table_rows from tables
where TABLE_SCHEMA = 'imora_scan'
order by table_rows desc;
MySQL LIMIT分页优化： SELECT * FROM `api_statistic` as apis
INNER JOIN (select id from api_statistic as ap2 limit 1410000,10 ) as c using(id);
把字段合并成一条记录返回: select GROUP_CONCAT(COLUMN_NAME) from information_schema.COLUMNS where table_name = 'biz_employee_cards';
select COLUMN_NAME from information_schema.COLUMNS where table_name = 'your_table_name' and table_schema = 'your_db_name';
GROUP_CONCAT ( url SEPARATOR " @ " )