mysql的六中排序

1、正序：

order by id asc

2、倒序

order by id desc

3、filed()函数自定义

order by field(state,300,700) desc, o.id desc

4、把null强制放到后面

order by  IF(ISNULL(m.media_identifier),1,0), field(saler_modify_flg,1) desc, pt_new_vertify asc,

5、把null强制放到前面

ORDER BY IF(ISNULL(update_date),0,1) 

6、在多种状态下，把其中几种前置：

order by(case when o.state=400 then 0 when o.state=500 and eome.order_effect_flg=0 and om.saler_vertify=1 then 1 when o.state=550 and eome.order_effect_flg=0 and om.saler_vertify=1 then 2 when o.state=600 and om.saler_vertify=1 then 3 else 99 end),om.id desc