MySQL基本操作

显示存在的现有数据库：

Show databases;

创建数据库：

Create database  database_name;

删除数据库：

Drop database database_name;

选择数据库：

Use test;

显示数据库的所有表格：

Show tables;

创建一个表格：

Create  table  test_table(id int(4), user char(20), password char(20))

删除表格：

Drop table test_table;

查询表格中的全部内容：

Select  *  from  leibusi;

查询表格中的部分内容：

Select *  from  leibusi  where id<3;Select  username  from leibusi;Select  username  from leibusi where id<3;Select  *  from  leibusi  where  username='yun';Select  id,username  from  leibusi;Select  *  from   leibusi  where  username  like  'tun';任意匹配：Select  *  from  leibusi  where  username like  '%u%'; 

向表格中插入数据：

Insert  into  leibusi  values(5,'test',99999);Insert  into  leibusi(id,username,QQ)  values(8,'xxxx',8888);

删除表格中数据：

Delete  from  leibusi  where  username='xxxx';

更改表格中数据：

Update  leibusi  set  username='ssss'   where  QQ=99999;

正序排序（默认）：

Select * from  leibusi order by id;

倒序排序：

Select  *  from  leibusi   order  by   id  desc;

分组：

Select  *  from  leibusi  group  by  username;

分组统计数目:

Select  username ,count(*)  from  leibusi  group  by  username;