sql - 如何从特定的大约中获取顶行。使用 sql server 2008 的百分比？

Question

我需要大约。每个日期的 30% 数据。

id     name   datecol
-----------------------
1       A     2016-11-11
2       B     2016-11-11
3       C     2016-11-11
4       D     2016-11-11
5       E     2016-11-11
6       F     2016-11-11
7       G     2016-11-11
8       H     2016-11-11
9       I     2016-11-11
10      J     2016-11-11
11      A1    2016-11-12
12      B1    2016-11-12
13      C1    2016-11-12
14      D1    2016-11-13
15      E1    2016-11-13
16      F1    2016-11-14
17      G1    2016-11-14
18      H1    2016-11-14
19      I1    2016-11-14
20      J1    2016-11-14

In this case i have

2016-11-11共10行
2016-11-12共3行
2016-11-13共2行
2016-11-14共5行

i need like this by approx. 30 percentage of top rows from each date,

id     name   datecol
-----------------------
1       A     2016-11-11
2       B     2016-11-11
3       C     2016-11-11
11      A1    2016-11-12
14      D1    2016-11-13
16      F1    2016-11-14
17      G1    2016-11-14

提前致谢。

Answer 1

使用 ROW_NUMBER() 尝试此查询获取行号和 COUNT() OVER ()获取每个日期的总计数:

WITH CTE AS 
(
  SELECT T.*,
         ROW_NUMBER() OVER (PARTITION BY datecol ORDER BY Name) as RowNum,
         COUNT(*) OVER (PARTITION BY datecol) as Total
    FROM Table as T
)
SELECT id,name,datecol 
  FROM CTE 
 WHERE RowNum <= CEILING(Total*0.30)

结果:

1   A   2016-11-11
2   B   2016-11-11
3   C   2016-11-11
11  A1  2016-11-12
14  D1  2016-11-13
16  F1  2016-11-14
17  G1  2016-11-14