在 SQL Server 中以动态范围显示计数

Question

我正在根据表中的最大值创建范围。例如，如果表中的最大值为 45，那么它将创建 0-10 11-20 21-30 31-40 41-50 之类的范围，然后希望在该范围内显示计数。下面是我在 SQL 中尝试的内容

DECLARE @VariableData TABLE (id INT, [label] NVARCHAR(50), PendingDays INT )

INSERT INTO @VariableData (id, [label], PendingDays) VALUES(1, 'Red', 5)
INSERT INTO @VariableData (id, [label], PendingDays) VALUES(2, 'Green', 7)
INSERT INTO @VariableData (id, [label], PendingDays) VALUES(3, 'Yellow', 25)
INSERT INTO @VariableData (id, [label], PendingDays) VALUES(4, 'Brown', 27)
INSERT INTO @VariableData (id, [label], PendingDays) VALUES(5, 'Black', 45)
INSERT INTO @VariableData (id, [label], PendingDays) VALUES(6, 'Red', 8)
INSERT INTO @VariableData (id, [label], PendingDays) VALUES(7, 'Red', 11)
INSERT INTO @VariableData (id, [label], PendingDays) VALUES(8, 'Green', 22)
INSERT INTO @VariableData (id, [label], PendingDays) VALUES(9, 'Black', 1)

SELECT * 
FROM @VariableData

我得到这个结果：

我想显示如下结果

有什么帮助吗？

Answer 1

您可以计算范围，然后根据范围的计算分为五组：

select vd.*,
       floor((pendingdays - min_pendingdays) * 5.0 / (max_pendingdays - min_pendingdays + 1)) as tile
from (select vd.*,
             min(pendingdays) over () as min_pendingdays,
             max(pendingdays) over () as max_pendingdays
      from VariableData vd
     ) vd;

这会将结果放在行中。您可以将这些聚合到列中：

select label,
       sum(case when tile = 0 then 1 end) as tile_1,
       sum(case when tile = 1 then 1 end) as tile_2,
       sum(case when tile = 2 then 1 end) as tile_3,
       sum(case when tile = 3 then 1 end) as tile_4,
       sum(case when tile = 4 then 1 end) as tile_5
from (select vd.*,
             floor((pendingdays - min_pendingdays) * 5.0 / (max_pendingdays - min_pendingdays + 1)) as tile
      from (select vd.*,
                   min(pendingdays) over () as min_pendingdays,
                   max(pendingdays) over () as max_pendingdays
            from VariableData vd
           ) vd
     ) vd
group by label;

唯一需要注意的是，您不能根据数据中的值来命名列。这需要动态 SQL。

Here 是一个 dbfiddle。

Answer 2

最简单的方法是将 CASE 与聚合一起使用。

SELECT [label], 
       SUM(CASE WHEN Pending Days BETWEEN 0 AND 10 THEN 1 ELSE 0 END) AS [0-10],
       SUM(CASE WHEN Pending Days BETWEEN 11 AND 20 THEN 1 ELSE 0 END) AS [11-20]
FROM @VariableData
GROUP BY [label]