多表联合查询
select a.*,b.*,c.* from a INNER JOIN b ON a.cid=b.cid INNER JOIN c ON c.cid=a.cid where a.cid=2 and a.id =3
删除多条
删除 id为 3 ，4 5 8 9的记录
delete from language_flash where id=3 or id=4 or id=8 现在这个or太多 比较2b
应使用in
delete from language_flash where id in (1,3,4,5);
查询表里的所有列名
select COLUMN_NAME from information_schema.columns where table_name='skill_attach_status_tbl'
