Question

在SQL Server中，我有两个日期列x和y列，我想计算这两个日期之间的频率，如果是每月，每季度或每年。

我试过自己，但似乎不正确

代码：

CASE WHEN ROUND(DATEDIFF(d, ISNULL(RV.[x], ''), ISNULL(RV.[y], ''))/30.0, 1) <= 1 THEN 'MONTHLY'    
     WHEN ROUND(DATEDIFF(d, ISNULL(RV.[x], ''), ISNULL(RV.[y], ''))/30.0, 1) BETWEEN 1 AND 3 THEN 'QUARTERLY'   
     ELSE 'ANNUALLY'  
END  FREQUENCY

如果有人能帮我正确编码，我将不胜感激。

谢谢，非常感谢

Answer 1

如果你在日期的某些NULL值的模拟数据上运行它，你会注意到DATEDIFF有时会返回负值。
这将使CASE返回＆＃34;每月＆＃34;出于错误的原因。

不要做ISNULL。这样，DATEDIFF将为那些返回NULL并被评估为＆＃34;年度＆＃34;。

此外，您还可以在f.e.中获取DATEDIFF。几个月，这可以简化您的查询。

declare @TestTable table (x date, y date);

declare @y date = '2017-08-15'; 

insert into @TestTable (x,y) values
(dateadd(day,-10,@y),@y),
(dateadd(day,-30,@y),@y),
(dateadd(day,-60,@y),@y),
(dateadd(day,-240,@y),@y),
(null,@y),
(dateadd(month,-2,@y),null);

select RV.*,
/* 
DATEDIFF(day, RV.[x], RV.[y]) as monthdiff,
DATEDIFF(month, RV.[x], RV.[y]) as monthdiff,
DATEDIFF(quarter, RV.[x], RV.[y]) as quarterdiff,
DATEDIFF(year, RV.[x], RV.[y]) as yeardiff,
*/
CASE 
 WHEN DATEDIFF(month, RV.[x], RV.[y]) = 0 THEN 'MONTHLY'  
 WHEN DATEDIFF(quarter, RV.[x], RV.[y]) = 0 THEN 'QUARTERLY'
 WHEN DATEDIFF(year, RV.[x], RV.[y]) = 0 THEN 'ANNUALLY'
 ELSE 'ANNUALLY?'
END FREQUENCY
from @TestTable RV;

返回：

x           y           FREQUENCY
----------  ----------  ----------
2017-08-05  2017-08-15  MONTHLY
2017-07-16  2017-08-15  QUARTERLY
2017-06-16  2017-08-15  ANNUALLY
2016-12-18  2017-08-15  ANNUALLY?
NULL        2017-08-15  ANNUALLY?
2017-06-15  NULL        ANNUALLY?

还检查此测试SQL的结果：

select RV.*, 
DATEDIFF(day, x, y) as daydiff,
DATEDIFF(month, x, y) as monthdiff,
DATEDIFF(quarter, x, y) as quarterdiff,
case when DATEDIFF(quarter, RV.[x], RV.[y]) = 0 then 'yes' else 'no' end as same_quarter
from (values 
('2017-01-15','2017-03-31'),
('2017-01-15','2017-04-01')
) as RV(x,y);

SQL - 计算两个日期之间的频率（每月，每季度和每年）

1 个答案: