汇总日期范围

Question

我与创建一个查询来汇总日期范围，同时利用两个场连续分组挣扎 - 基本上我试图把这个：

|Key|Valid|DateFrom |DateTo | 
| 1| 0|2001-01-01|2001-01-31| 
| 1| 0|2001-02-01|2001-02-20| 
| 1| 1|2001-02-21|2001-02-28| 
| 1| 0|2001-03-01|2001-03-15| 
| 2| 1|2001-01-01|2001-01-31| 
| 2| 0|2001-02-01|2001-02-20| 
| 2| 0|2001-02-21|2001-02-28| 
| 2| 1|2001-03-01|2001-03-15| 

到这一点：

|Key|Valid|DateFrom |DateTo | 
| 1| 0|2001-01-01|2001-02-20| 
| 1| 1|2001-02-21|2001-02-28| 
| 1| 0|2001-03-01|2001-03-15| 
| 2| 1|2001-01-01|2001-01-31| 
| 2| 0|2001-02-01|2001-02-28| 
| 2| 1|2001-03-01|2001-03-15| 

当然，按键，有效的简单min（DateFrom），max（DateTo）组不起作用，因为它不尊重日期范围的时间顺序。应该指出，每个密钥和有效组在日期范围内没有差距。

我已经搜索了广泛的解决方案（在这里和网络上的其他地方），并发现了很多使用OVER和CTE的组合日期的解决方案（他们都尝试过），但我认为问题在于我试图以分为两个不同的组别。我也尝试将范围转换为单独的日期，但我似乎无法按照两个组的时间顺序将它们卷起来。

任何帮助，将不胜感激。谢谢。

Answer 1

我没有在我面前SQL客户端，但你可以做这样的事情......

WITH 
    sequenced_data 
AS 
(
    SELECT 
    ROW_NUMBER() OVER (PARTITION BY Key  ORDER BY DateFrom) AS KeyRow, 
    ROW_NUMBER() OVER (PARTITION BY Key, Valid ORDER BY DateFrom) AS KeyValidRow, 
    * 
    FROM 
    yourData 
) 
SELECT 
    Key, 
    Valid, 
    MIN(DateFrom) AS DateFrom, 
    MAX(DatTo) AS DateTo 
FROM 
    sequenced_data 
GROUP BY 
    Key, 
    Valid, 
    KeyRow - KeyValidRow 
ORDER BY 
    Key, 
    MIN(DateFrom) 

可视化与您的数据......

|Key|Valid|DateFrom |DateTo |KeyRow|KeyValidRow|KeyRow - KeyValidRow 
| 1| 0|2001-01-01|2001-01-31|  1|   1|  0 
| 1| 0|2001-02-01|2001-02-20|  2|   2|  0 
| 1| 1|2001-02-21|2001-02-28|  3|   1|  2 
| 1| 0|2001-03-01|2001-03-15|  4|   3|  1 
| 2| 1|2001-01-01|2001-01-31|  1|   1|  0 
| 2| 0|2001-02-01|2001-02-20|  2|   1|  1 
| 2| 0|2001-02-21|2001-02-28|  3|   2|  1 
| 2| 1|2001-03-01|2001-03-15|  4|   2|  2 

虽然KeyRow - KeyValidRow做不一定会告诉你很多，它确实为每个组提供了明显的价值，所以对于GROUP BY来说就足够了。

无论组中有多少条记录，它都能正常工作，但假设数据中没有空白或重叠。

Answer 2

您可以通过首先计算关键行（即有效或关键更改）然后链接到该组的最大日期来完成。

编辑 - 重写处理Dems标记的角落案例。这VERSON也有间隙涉及序列中

with keyItems as ( 
    -- First find all the "Key Frames" 
    select d.* 
from 
    data d 
left outer join data d2 
    on d.[Key]=d2.[key] and d.valid=d2.valid and d.dateFrom = DateAdd(d,1,d2.dateto) 
where d2.[key] is null 
), 
ordered as ( 
    -- This is to provide a sequence number for the main query against these key frames 
    select 
    ROW_NUMBER() over (partition by [key] order by datefrom) as row, 
    * 
    from keyItems 
), 
rangeends([key],row,dateto) as (
select o.[key],o.row-1,MAX(d.DateTo) 
from ordered o left outer join data d on d.[key]=o.[key] and d.DateTo < o.DateFrom 
group by o.[key],o.row-1 
union all 
select o.[key],MAX(o.row),MAX(d.dateto) 
from ordered o inner join data d on d.[key]=o.[key] 
group by o.[key] 
) 
select 
    o1.[Key], 
    o1.Valid, 
    o1.DateFrom, 
    coalesce(r.dateto,o1.dateTo) as DateTo 
    from ordered o1 
    left outer join rangeends r on r.[key]=o1.[Key] and r.row=o1.row 

Answer 3

我不能拿出任何短使用光标。但是，这确实有效：

declare @example table (tKey int, Valid int, DateFrom date, DateTo date); 

insert into @example values (1, 0, '2001-01-01', '2001-01-31'); 
insert into @example values (1, 0, '2001-02-01', '2001-02-20'); 
insert into @example values (1, 1, '2001-02-21', '2001-02-28'); 
insert into @example values (1, 0, '2001-03-01', '2001-03-15'); 
insert into @example values (2, 1, '2001-01-01', '2001-01-31'); 
insert into @example values (2, 0, '2001-02-01', '2001-02-20'); 
insert into @example values (2, 0, '2001-02-21', '2001-02-28'); 
insert into @example values (2, 1, '2001-03-01', '2001-03-15'); 

declare @output table (tKey int, Valid int, DateFrom date, DateTo date); 

DECLARE ex_cursor CURSOR FOR 
    select 
     tKey,Valid,DateFrom,DateTo 
    from 
     @example 
    order by tKey, DateFrom 

DECLARE @tKey int 
DECLARE @Valid int 
DECLARE @DateFrom date 
DECLARE @DateTo date 

DECLARE @last_tKey int 
DECLARE @last_Valid int 
DECLARE @min_Date date 
DECLARE @max_Date date 

OPEN ex_cursor; 

FETCH NEXT FROM ex_cursor 
INTO @tKey, @Valid, @DateFrom, @DateTo; 
SET @last_tKey = @tKey; 
SET @last_Valid = @Valid; 
SET @min_Date = @DateFrom; 
SET @max_Date = @DateTo; 

WHILE @@FETCH_STATUS = 0 
BEGIN 
    IF (@last_tKey <> @tKey OR @last_Valid <> @Valid) 
     BEGIN 
      -- output results 
      INSERT INTO @output SELECT @last_tKey, @last_Valid, @min_Date, @max_Date 
      -- reset values 
      SET @last_tKey = @tKey; 
      SET @last_Valid = @Valid; 
      SET @min_Date = @DateFrom; 
      SET @max_Date = @DateTo; 
     END 
    ELSE 
     BEGIN 
      IF (@DateTo > @max_Date) SET @max_Date = @DateTo 
     END 
    FETCH NEXT FROM ex_cursor 
    INTO @tKey, @Valid, @DateFrom, @DateTo 
END 
-- output one more time at end 
INSERT INTO @output SELECT @last_tKey, @last_Valid, @min_Date, @max_Date 
CLOSE ex_cursor; 
DEALLOCATE ex_cursor; 

SELECT * FROM @output ORDER BY tKey, DateFrom