Question

一个真正的头脑风暴就在这里。

我想标记de X1之间的过渡。因此，从A-> B，B-> A和B-> C，C-> B过渡。

这是为了将我的数据集减少为仅具有过渡的记录。

最终目标是计算从最后一次出现X1 A到第一次出现X1 B的日期之间的天数。

例如：

ID1->从A到B的过渡，日期为2018-01-20和2018-02-01。那么答案必须是x天数之间。

OR

示例2：ID1->从A过渡到B，日期为2018-02-16和2018-03-01。然后答案必须是x天数之间。

ID      X1      Date  
1       A       2018-01-01  
1       A       2018-01-20  
1       B       2018-02-01  
1       A       2018-02-15  
1       A       2018-02-16  
1       B       2018-03-01  
2       B       2018-01-01  
2       C       2018-03-05  
2       C       2018-03-06   
2       C       2018-03-08  
2       B       2018-03-20

我已经有了这个循环，但是这个循环花费的时间太长（每条记录0.3秒）：

DECLARE @Loop INT    
DECLARE @MAXROWS INT    
SET @Loop = 1    
SET @MAXROWS = (SELECT COUNT (*) FROM Y_Table)    
WHILE (@Loop <= @MAXROWS)    
BEGIN    
UPDATE Y_Table    
SET Y_Table.Test_MIN = (CASE WHEN     
(SELECT Y_Table.ID FROM Y_Table WHERE LIFE_CYCLE = @Loop) =   
(SELECT Y_Table.ID FROM Y_Table WHERE LIFE_CYCLE = @Loop + 1) AND  
(SELECT Y_Table.Date FROM Y_Table WHERE LIFE_CYCLE = @Loop) <   
(SELECT Y_Table.Date FROM Y_Table WHERE LIFE_CYCLE = @Loop + 1) AND  
(SELECT Y_Table.X1 FROM Y_Table WHERE LIFE_CYCLE = @Loop) <>   
(SELECT Y_Table.X1 FROM Y_Table WHERE LIFE_CYCLE = @Loop + 1)  
THEN '1' ELSE '0' END)  
FROM Y_Table  
WHERE   
LIFE_CYCLE = @Loop  
UPDATE Y_Table  
SET Y_Table.Test_MAX = (CASE WHEN   
(SELECT Y_Table.ID FROM Y_Table WHERE LIFE_CYCLE = @Loop) =   
(SELECT Y_Table.ID FROM Y_Table WHERE LIFE_CYCLE = @Loop + 1) AND  
(SELECT Y_Table.Date FROM Y_Table WHERE LIFE_CYCLE = @Loop) <   
(SELECT Y_Table.Date FROM Y_Table WHERE LIFE_CYCLE = @Loop + 1) AND  
(SELECT Y_Table.X1 FROM Y_Table WHERE LIFE_CYCLE = @Loop) <>   
(SELECT Y_Table.X1 FROM Y_Table WHERE LIFE_CYCLE = @Loop + 1)  
THEN '1' ELSE '0' END)  
FROM Y_Table  
WHERE   
LIFE_CYCLE = @Loop + 1  
PRINT @Loop  
SET @Loop = @Loop + 1  
END

如何解决这个问题？

Answer 1

使用LEAD获取下一行
过滤到不同的地方（=过渡）

类似这样的东西

DECLARE @data table (ID int, X1 char(1), myDate  date)

INSERT @data VALUES (1, 'A', '2018-01-01'),  
    (1, 'A', '2018-01-20'),  
    (1, 'B', '2018-02-01'),  
    (1, 'A', '2018-02-15'),  
    (1, 'A', '2018-02-16'),  
    (1, 'B', '2018-03-01'),  
    (2, 'B', '2018-01-01'),  
    (2, 'C', '2018-03-05'),  
    (2, 'C', '2018-03-06'),   
    (2, 'C', '2018-03-08'),  
    (2, 'B', '2018-03-20');

WITH GetNextRows AS (
    SELECT
        *,
        NextX1 = LEAD (X1) OVER (PARTITION BY ID ORDER BY myDate),
        NextDate = LEAD (myDate) OVER (PARTITION BY ID ORDER BY myDate)
    FROM
        @data
    )
SELECT 
    *,
    Transation = CONCAT(X1, ' -> ', NextX1),
    DaysGap = DATEDIFF(DAY, myDate, NextDate)
FROM
    GetNextRows
WHERE
    NextX1 <> X1;


ID  X1  myDate  NextX1  NextDate    Transation  DaysGap
1   A   2018-01-20  B   2018-02-01  A -> B      12
1   B   2018-02-01  A   2018-02-15  B -> A      14
1   A   2018-02-16  B   2018-03-01  A -> B      13
2   B   2018-01-01  C   2018-03-05  B -> C      63
2   C   2018-03-08  B   2018-03-20  C -> B      12

Answer 2

您可以使用LAG来获取先前的X1和Date值。如果当前的X1值与先前的值不同，则您可以进行转换，并可以按天计算差异。

DECLARE @DataSource TABLE
(
    [ID] SMALLINT
   ,[X1] CHAR(1)
   ,[Date] DATE
);

INSERT INTO @DataSource ([ID], [X1], [Date])
VALUES ('1', 'A', '2018-01-01')
      ,('1', 'A', '2018-01-20')
      ,('1', 'B', '2018-02-01')
      ,('1', 'A', '2018-02-15')
      ,('1', 'A', '2018-02-16')
      ,('1', 'B', '2018-03-01')
      ,('2', 'B', '2018-01-01')
      ,('2', 'C', '2018-03-05')
      ,('2', 'C', '2018-03-06')
      ,('2', 'C', '2018-03-08')
      ,('2', 'B', '2018-03-20');

SELECT *
     ,IIF
     (
        [X1] <> LAG([X1], 1, NULL) OVER(PARTITION BY [ID] ORDER BY [Date] ASC)
       ,DATEDIFF(DAY, LAG([Date], 1, NULL) OVER(PARTITION BY [ID] ORDER BY [Date] ASC), [Date])
       ,NULL
    ) AS [TransitionInDays]
FROM @DataSource;

请注意，您需要SQL Server 2012+才能使用LAG。让我知道是否不是这种情况。

在记录级别上标记差异

2 个答案: