Question

如何排除所有与我的平均声明相反的日期值？

查询：

select Avg_DayDiff case when Avg_DayDiff > 0

from(

SELECT DATEDIFF(DAY, xx, yy) AS Avg_DayDiff

FROM Database1.dbo.tbl_1

where  
        month(datecompleted) = month(dateadd(month,-1,current_timestamp))
       and year(datecompleted) = year(dateadd(month,-1,current_timestamp))
       and ApprovalRequiredFrom = 'GRM'

       ) temptable

我的查询从第一行返回语法错误（select语句）我还在学习，所以任何提示都非常感谢！

我正在寻找的结果是只返回约会，如果＃＆gt; 0，所以我可以平均一下。

感谢

Answer 1

请尝试在where声明中使用case when子句作为主查询，而不是select：

select Avg_DayDiff 
from(
      SELECT DATEDIFF(DAY, xx, yy) AS Avg_DayDiff
      FROM Database1.dbo.tbl_1
      where  
       month(datecompleted) = month(dateadd(month,-1,current_timestamp))
       and year(datecompleted) = year(dateadd(month,-1,current_timestamp))
       and ApprovalRequiredFrom = 'GRM'
) temptable
where Avg_DayDiff > 0

Answer 2

您可以简单地排除例如

的值

    SELECT DATEDIFF(DAY, xx, yy) AS Avg_DayDiff
    FROM Database1.dbo.tbl_1
    where  month(datecompleted) = month(dateadd(month,-1,current_timestamp))
        and year(datecompleted) = year(dateadd(month,-1,current_timestamp))
           and ApprovalRequiredFrom = 'GRM'
            and  DATEDIFF(DAY, xx, yy) > 0

Answer 3

使用abs（）函数，它只返回正值。

SELECT abs(DATEDIFF(DAY, xx, yy)) AS Avg_DayDiff

以上将足以获得正值并避免负值。

SQL - 如何从datediff函数中排除负值

3 个答案: