SQL Server行数

Question

我想根据下面的样品实现行编号：

StartOfWeek Total RowNumber 
----------------------------- 
1/17/2016 8  1 
1/24/2016 8  1 
1/31/2016 10  2 
2/7/2016 10  2 
2/14/2016 14  3 
2/21/2016 10  4 
2/28/2016 10  4 

我怎样才能做到这一点？我尝试了dense_rank，但似乎无法获得预期的RowNumber。

谢谢！

Answer 1

可以使用CTE为这个和自加入

CREATE TABLE test (
    StartOfWeek DATETIME, 
    Total INT 
    ) 
INSERT INTO test 
VALUES ('1/17/2016',8), 
     ('1/24/2016',8), 
     ('1/31/2016',10), 
     ('2/7/2016',10), 
     ('2/14/2016',14), 
     ('2/21/2016',10), 
     ('2/28/2016',10) 

;WITH cte AS (
    SELECT *, 
      ROW_NUMBER() OVER (ORDER BY StartOfWeek) Rn 
    FROM test 
) 
SELECT c1.StartOfWeek, 
     c1.Total, 
     -- incremement by 1 if Total value changes 
     SUM(CASE WHEN c1.Total= c2.Total THEN 0 
       ELSE 1 END) OVER (ORDER BY c1.Rn) AS RowNumber 
FROM cte c1 
     LEFT JOIN cte c2 ON c1.Rn = c2.Rn + 1 

Result 

StartOfWeek    Total  RowNumber 
----------------------- ----------- ----------- 
2016-01-17 00:00:00.000 8   1 
2016-01-24 00:00:00.000 8   1 
2016-01-31 00:00:00.000 10   2 
2016-02-07 00:00:00.000 10   2 
2016-02-14 00:00:00.000 14   3 
2016-02-21 00:00:00.000 10   4 
2016-02-28 00:00:00.000 10   4