在 Snowflake 查询中遇到除以零错误

Question

我有以下雪花查询，其中出现除以零错误...你能帮我吗...

with cte1 as 
(select * from "coe.cup"
where typeofcare ='AM'
and status ='DONE'
and review ='false'
and date (assigneddate)>='2021-04-01'), cte2 as(
select cast(completed as date) completeddate ,iscode
 ,iff(iscode=1,datediff(minute,assigneddate,coded),0) codeddatetime
 ,iff(iscode=0,datediff(minute,assigneddate,qaed),0) qaeddatetime
 ,datediff(minute,assigneddate,completed) overall  from 
 (select *,iff(qaed='1900-01-01 00:00:00.0000000',1,0) iscode from cte1)a )
 select completeddate 
 ,sum(iff(iscode=1,1,0)) noofvisitbillscoded
 ,sum(iff(iscode=1,0,1)) noofvisitbillscodedandqaed
 ,count(1) totalvisitbillscompleted
 ,cast(sum(codeddatetime)/sum(iff(iscode=1,1,0)) as float)/60 averagetimeforcodedvisitbills
 ,cast(sum(qaeddatetime)/sum(iff(iscode=1,0,1)) as float)/60  averagetimeforcodedandqaedvisitbills
 ,cast(sum(overall)/count(1) as float)/60 overallaveragetime
 from cte2
 group by completeddate

Answer 1

我假设这是由于 /sum(iff(iscode=1,1,0)) 而发生的，其中可能有时 returns 0.

处理被零除的一种方法是使用NULLIF

NULLIF( <expr1> , <expr2> )

returns NULL 如果 expr1 等于 expr2，否则 returns expr1.

因此，在您的代码中，例如 sum(iff(iscode=1,1,0))，您可以将其替换为：

NULLIF(sum(iff(iscode = 1, 1, 0)), 0)

然后这应该 return NULL 而不是导致被零除。

Answer 2

另一种选择是使用 DIV0 函数，例如：

DIV0(sum(codeddatetime),sum(iff(iscode=1,1,0))

更多信息在这里：https://docs.snowflake.com/en/sql-reference/functions/div0.html

Answer 3

当涉及除法时，除数可以用 NULLIFZERO:

处理

NULLIFZERO( )

Returns NULL if the argument evaluates to 0; otherwise, returns the argument.

第二个模式 sum(iff(iscode=1,1,0)) 是模拟过滤后的 COUNT 的条件总和。它可以进一步简化 COUNT_IF

COUNT_IF( )

Returns the number of records that satisfy a condition.

总结一下：

,cast(sum(codeddatetime)/sum(iff(iscode=1,1,0)) as float)/60 

=>
,SUM(codeddatetime)/NULLIFZERO(COUNT_IF(iscode=1))/60 

=> if iscode is boolean column then:
,SUM(codeddatetime)/NULLIFZERO(COUNT_IF(iscode))/60

在 Snowflake 查询中遇到除以零错误

Divide by Zero Error encountered in Snowflake Query

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snowflake-cloud-data-platform