SQL 的坑1 除法“”不可用“”

今天工作中遇见 一问题，有5各部分，现要求5个部分各自的比例，SQL语句没有问题，后来还试了“加”，“减”，“乘”，“Round”，结果都对，唯独“除法”得不到结果。

之前的语句和结果

select Date_1,
	isnull(APP,0) as APP,
	isnull(邮件,0)as YouJ,
	isnull(微信,0) as WeiX,
	isnull(微博,0) as WeiB,
	isnull(电信渠道,0) as DXQD,
	(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0))as total,

	isnull(APP,0)+(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0)) as APP_Ratio_text,
	ROUND(isnull(邮件,0)/(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0)),6) as YouJ_Ratio,
	ROUND(isnull(微信,0)*(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0)),6) as WeiX_Ratio_test,
	isnull(微博,0)/(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0)) as WeiB_Ratio,
	isnull(电信渠道,0)/(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0)) as DXQD_Ratio
	
from(
select convert(varchar(100),date_1,111) as Date_1,promotion_unit,sum(amount) as amount1
from dbo.EDM_message_consume('2016/06/26','2016/06/27')
where project_type is not null 
group by promotion_unit,date_1) newtb
pivot (sum(amount1)  for newtb.promotion_unit in (APP,邮件,微信,微博,电信渠道)) as pivottb

后同事提醒试乘1.0,遂解决 如下

select Date_1,
	isnull(APP,0) as APP,
	isnull(邮件,0)as YouJ,
	isnull(微信,0) as WeiX,
	isnull(微博,0) as WeiB,
	isnull(电信渠道,0) as DXQD,
	(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0))as total,

	isnull(APP,0)*1.0/(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0)) as APP_Ratio,
	isnull(邮件,0)*1.0/(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0)) as YouJ_Ratio,
	isnull(微信,0)*1.0/(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0)) as WeiX_Ratio,
	isnull(微博,0)*1.0/(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0)) as WeiB_Ratio,
	isnull(电信渠道,0)*1.0/(isnull(APP,0)+isnull(邮件,0)+isnull(微信,0)+isnull(微博,0)+isnull(电信渠道,0)) as DXQD_Ratio
	
from(
select convert(varchar(100),date_1,111) as Date_1,promotion_unit,sum(amount) as amount1
from dbo.EDM_message_consume('2016/06/26','2016/06/27')
where project_type is not null 
group by promotion_unit,date_1) newtb
pivot (sum(amount1)  for newtb.promotion_unit in (APP,邮件,微信,微博,电信渠道)) as pivottb