Question

我一直在尝试编写一个案例陈述，如下所示

case when datediff(week,cast(cast(tourney_date as char(8)) as date, current_timestamp) >104 then 0
     when datediff(week,cast(cast(tourney_date as char(8)) as date, current_timestamp) <=13 then 1
     when datediff(week,cast(cast(tourney_date as char(8)) as date, current_timestamp) between 14 and 104 
     then cast(((datediff(week,cast(cast(tourney_date as char(8)) as date, current_timestamp)-13)/91) as numeric(6,5) end as multiplier

然而，当datediff返回14到104之间的值时，这不会返回非0.0000值。为了测试这个，我试图让一个非常基本的测试工作

declare @test as numeric(6,5)
set @test=72/91
print @test

我仍然得到0.00000？我犯了什么基本错误？

提前致谢。

Answer 1

错误是integer division：

如果整数被除数除以整数除数，则结果是一个整数，其截断结果的任何小数部分。

global._ = _;返回一个整数。

你在这里遇到问题可能是因为你在之前将划分为数字值。或者，这是因为SQL Server发现CASE表达式的两个输出是整数，因此它使整个列成为整数。请记住，列只能获得一种数据类型。

尝试：

DATEDIFF(week,@datetime,@datetime)

我试图修复你丢失的括号，但可能错过了一些。

另外：我可以理解case when datediff(week,cast(cast(tourney_date as char(8)) as date), current_timestamp) >104 then 0.0 when datediff(week,cast(cast(tourney_date as char(8)) as date), current_timestamp) <=13 then 1.0 when datediff(week,cast(cast(tourney_date as char(8)) as date), current_timestamp) between 14 and 104 then cast(((datediff(week,cast(cast(tourney_date as char(8)) as date), current_timestamp)-13.0)/91.0) as numeric(6,5)) end as multiplier的唯一原因是因为cast(cast(tourney_date as char(8)) as date)尚未tourney_date或date。为了上帝的缘故，将日期存储为日期，而不是字符串或数字。

Answer 2

你可以通过做这样的事情来简化它

declare @tourney_date datetime = '2017-9-16 '
declare @new_date datetime = (select  DATEADD(day, DATEDIFF(day, 0, @tourney_date), 0))
select
case when datediff(week,@new_date, current_timestamp) >104 then 0
     when datediff(week,@new_date, current_timestamp) <=13 then 1
     when datediff(week,@new_date, current_timestamp) between 14 and 104 
     then cast(((datediff(week,@new_date, current_timestamp)-13)/91.0) as numeric(6,5)) end as multiplier

Answer 3

在Sql Server中，当你划分72/91时，它的意思是int / int结果是int。

示例：（int）0.79120 = 0

您可以尝试：

declare @test as numeric(6,5)
set @test=CAST(72 AS DECIMAL(5,1))/91
select @test union all
select 72.0/91 union all
select (72*1.0)/91

您可以在此处查看更多信息：SQL Server division query

SQL Server - 为什么calc给出0？

3 个答案: