mysql实用语句

1、增加字段：
alter TABLE v_resource add source_url varchar(255)

2、删除字段：
alter table v_live DROP COLUMN type

3、分组：
SELECT *,COUNT(*) as count from v_resource where 1=1 GROUP BY bitrate,framerate,dimension;

4、联合查询加分组：
select r.pic,r.dimension,r.bitrate,r.framerate,r.name,COUNT(*) as count from v_resource r left join v_program_epg p on p.sourceid=r.sourceid GROUP BY bitrate,framerate,dimension;

5、导出数据库
mysqldump -u root -p 123456 vlive_xj > vlive1.sql;