SQL Server 范围计数

Question

我有一个 SQL Server 表，其中一列代表时间，而另一列代表一个 ID，如下所示：

    Datum                     SomeID 
2017-01-01 07:44:57.840         1   
2017-01-02 07:45:10.093         2   
2017-01-02 07:45:21.557         3    
2017-01-03 09:07:21.253         2  
2017-01-05 09:07:42.680         1 
2017-01-06 09:07:49.007         5 

我正在寻找一个 SQL 查询或存储过程，它将时间单位作为输入（例如“YY”、“MM”、“DD”、“HH”）并返回一个表，其中每个表都有唯一的 ID 计数时间间隔。如果没有找到该间隔的记录，则计数应为零。

在这种情况下，假设'DD'作为时间单位，结果应该是：

Time interval      Count
2017-01-01           1
2017-01-02           2
2017-01-03           1
2017-01-04           0
2017-01-05           1
2017-01-06           1

Answer 1

可能最简单的方法是动态SQL：

declare @timeunit nvarchar(255);
declare @sql nvarchar(max);

set timeunit = N'hh';

set @sql = '
select dateadd(@timeunit, datediff(@timeunit, 0, datum), 0) as dt, count(*)
from t
group by dateadd(@timeunit, datediff(@timeunit, 0, datum), 0) 
';

set @sql = replace(@sql, '@timeunit', @timeunit);

exec sp_executesql @sql;

我不喜欢将用户输入放入这样的查询中。不过，您可以轻松地检查它的有效值：

(case when @timeunit in ('year', 'yy', 'month', 'mm',  . . .) then . . .
 end)

Answer 2

我经常使用表值函数来创建动态日期/时间范围。一个计数/日历表也可以解决问题。但是，该功能提供了更多的灵活性。参数为日期范围、日期部分和增量。

我还应该注意您的特定问题，我使用 Format()。此功能有一些很棒的功能，但它的性能未知。

示例：

Declare @YourTable table (Datum datetime,SomeID int)
Insert Into @YourTable values
('2017-01-01 07:44:57.840',1),
('2017-01-02 07:45:10.093',2),   
('2017-01-02 07:45:21.557',3),    
('2017-01-03 09:07:21.253',2),  
('2017-01-05 09:07:42.680',1), 
('2017-01-06 09:07:49.007',5)

Declare @DispFormat varchar(10)='yyyy-MM-dd'   --<< Standard Format() options
Declare @DatePart   varchar(10)='DD'           --<< YY,MM,DD,HH,MI,SS
Declare @Increment  int        = 1             --<< Set Increment

Declare @DateR1 datetime
Declare @DateR2 datetime
Select @DateR1=min(Datum),@DateR2=max(Datum) from @YourTable  --<< Can be set manually if desired

Select A.TimeInterval 
      ,Count        = count(Distinct SomeID)
 From  (Select *,TimeInterval = format(RetVal,@DispFormat) From [dbo].[udf-Range-Date](@DateR1,@DateR2,@DatePart,@Increment)) A
 Left  Join @YourTable B on format(A.RetVal,@DispFormat) = format(B.Datum,@DispFormat)
 Group By  A.TimeInterval 

退货

TimeInterval    Count
2017-01-01      1
2017-01-02      2
2017-01-03      1
2017-01-04      0
2017-01-05      1
2017-01-06      1

UDF（如果有兴趣）

CREATE FUNCTION [dbo].[udf-Range-Date] (@R1 datetime,@R2 datetime,@Part varchar(10),@Incr int)
Returns Table
Return (
    with cte0(M)   As (Select 1+Case @Part When 'YY' then DateDiff(YY,@R1,@R2)/@Incr When 'QQ' then DateDiff(QQ,@R1,@R2)/@Incr When 'MM' then DateDiff(MM,@R1,@R2)/@Incr When 'WK' then DateDiff(WK,@R1,@R2)/@Incr When 'DD' then DateDiff(DD,@R1,@R2)/@Incr When 'HH' then DateDiff(HH,@R1,@R2)/@Incr When 'MI' then DateDiff(MI,@R1,@R2)/@Incr When 'SS' then DateDiff(SS,@R1,@R2)/@Incr End),
         cte1(N)   As (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)),
         cte2(N)   As (Select Top (Select M from cte0) Row_Number() over (Order By (Select NULL)) From cte1 a, cte1 b, cte1 c, cte1 d, cte1 e, cte1 f, cte1 g, cte1 h ),
         cte3(N,D) As (Select 0,@R1 Union All Select N,Case @Part When 'YY' then DateAdd(YY, N*@Incr, @R1) When 'QQ' then DateAdd(QQ, N*@Incr, @R1) When 'MM' then DateAdd(MM, N*@Incr, @R1) When 'WK' then DateAdd(WK, N*@Incr, @R1) When 'DD' then DateAdd(DD, N*@Incr, @R1) When 'HH' then DateAdd(HH, N*@Incr, @R1) When 'MI' then DateAdd(MI, N*@Incr, @R1) When 'SS' then DateAdd(SS, N*@Incr, @R1) End From cte2 )

    Select RetSeq = N+1
          ,RetVal = D 
     From  cte3,cte0 
     Where D<=@R2
)
/*
Max 100 million observations -- Date Parts YY QQ MM WK DD HH MI SS
Syntax:
Select * from [dbo].[udf-Range-Date]('2016-10-01','2020-10-01','YY',1) 
Select * from [dbo].[udf-Range-Date]('2016-01-01','2017-01-01','MM',1) 
*/

只是为了好玩...试试：

Declare @DispFormat varchar(10)='HH:00'
Declare @DatePart   varchar(10)='HH'   
Declare @Increment  int        = 1