T-SQL 递进编号分区

Question

我的目标是获得这样的记录集

date   flag   number
01     0      1
02     0      1
03     1      2
04     1      2
05     1      2
06     0      3
07     1      4
08     1      4

我只从 "date" 和 "flag" 的记录集开始。我正在尝试使用 T-SQL 排名和分区函数来计算 "number" 列。

正常排名会给出这样的结果：

 date   flag   number
    01     0      1
    02     0      1
    03     1      2
    04     1      2
    05     1      2
    06     0      1
    07     1      2
    08     1      2

有什么建议吗？

Answer 1

你可以试试这个：

DECLARE @DataSource TABLE
(
    [date] CHAR(2)
   ,[flag] BIT
);

INSERT INTO @DataSource ([date], [flag])
VALUES ('01', 0)
      ,('02', 0)
      ,('03', 1)
      ,('04', 1)
      ,('05', 1)
      ,('06', 0)
      ,('07', 1)
      ,('08', 1);

WITH DataSource ([date], [flag], [number]) AS
(
    SELECT [date]
          ,[flag]
          ,IIF(LAG([flag], 1, NULL) OVER (ORDER BY [date]) = [flag], 0, 1) 
    FROM @DataSource
)
SELECT [date]
      ,[flag]
      ,SUM([number]) OVER (ORDER BY [date] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS [number]
FROM DataSource
ORDER BY [date], [flag];

想法是使用 LAG 函数检查何时更改组：

IIF(LAG([flag], 1, NULL) OVER (ORDER BY [date]) = [flag], 0, 1)

然后，使用 BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW 到 SUM 组更改。

Answer 2

j,

SQL Server 2012 有许多新功能，例如 SQL Lead() and SQL Lag() functions. You can use the SQL Server Lag() function 可以解决您的需求

这是我的解决方案

with cte as (
select 
    date, flag, 
    LAG(flag, 1, NULL) OVER (ORDER BY date) AS preVal,
    case when flag = ISNULL( ( LAG(flag, 1, NULL) OVER (ORDER BY date) ), flag) then 0 else 1 end as i
from recordset
)
select
    cte.date,
    cte.flag,
    sum(cte2.i)+1 r
from cte
inner join cte as cte2 on cte.date >= cte2.date
group by cte.date, cte.flag
order by cte.date

Answer 3

您可以像这样在游标中填充它：

DECLARE  @Table TABLE (
[Date] [nvarchar](50) NULL,
[flag] [int] NULL,
[Number] [int] NULL
) 

DECLARE @Date nvarchar(50)
DECLARE @flag int
DECLARE @number int
DECLARE @flagnumber int
DECLARE @flagincrement int

DECLARE  MyCursor CURSOR FOR
SELECT [Date],FLag
FROM [LegOgSpass].[dbo].[testflag]
Order by [Date]

OPEN MyCursor
FETCH NEXT FROM MyCursor
INTO @Date,@flag

IF (@@FETCH_STATUS>=0)
BEGIN

SET @number = 1
SET @flagincrement = @flag

INSERT INTO @Table ([Date],[Flag],[Number])
VALUES(@Date,@flag,@number)

FETCH NEXT FROM MyCursor INTO @Date,@flag
END
WHILE (@@FETCH_STATUS<>-1)
BEGIN
IF (@@FETCH_STATUS<>-2)
IF @flagincrement = @flag 
SET @number = @number 

ELSE
SET @number = @number+1
SET @flagincrement = @flag

INSERT INTO @Table ([Date],[Flag],[Number])
VALUES(@Date,@flag,@number)
FETCH NEXT FROM MyCursor INTO @Date,@flag
END

CLOSE MyCursor
DEALLOCATE MyCursor

SELECT * FROM @Table

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