Question

我在SQL Server的数据库表中有以下数据：

MIMMAXPOINTS

Val_B列实际上应包含最低Vector，'BELOW'为Val_A，最高Vector，'ABOVE'为MINMAXPOINTS }}。因此，我们在MINMAXPOINTS 68.40 68.40 82.40 82.40 82.40 82.40 72.29 81.75 81.75 81.75中有以下值：

In [32]: import numpy as np 

In [33]: list_of_arrays = list(map(lambda x: x * np.ones(2), range(5)))

In [34]: list_of_arrays
Out[34]: 
[array([ 0.,  0.]),
 array([ 1.,  1.]),
 array([ 2.,  2.]),
 array([ 3.,  3.]),
 array([ 4.,  4.])]

In [37]: shape = list(list_of_arrays[0].shape)

In [38]: shape
Out[38]: [2]

In [39]: shape[:0] = [len(list_of_arrays)]

In [40]: shape
Out[40]: [5, 2]

In [41]: arr = np.concatenate(list_of_arrays).reshape(shape)

In [42]: arr
Out[42]: 
array([[ 0.,  0.],
       [ 1.,  1.],
       [ 2.,  2.],
       [ 3.,  3.],
       [ 4.,  4.]])

没有光标可以吗？

任何帮助将不胜感激！。

Answer 1

首先应用经典gaps-and-islands来确定组（差距/岛/上/下），然后为每个组计算MIN和MAX。

我假设ID列定义了行的顺序。

在SQL Server 2008上测试。这是SQL Fiddle。

示例数据

DECLARE @T TABLE
([Id] int, [dt] date, [Val_A] float, [Val_B] float, [Val_C] float, [Avg] float, 
[Vector] varchar(5));

INSERT INTO @T ([Id], [dt], [Val_A], [Val_B], [Val_C], [Avg], [Vector]) VALUES
(329, '2016-01-15', 78.09, 68.40, 70.29, 76.50, 'BELOW'),
(328, '2016-01-14', 79.79, 75.40, 76.65, 76.67, 'BELOW'),
(327, '2016-01-13', 81.15, 74.59, 79.00, 76.44, 'ABOVE'),
(326, '2016-01-12', 81.95, 77.04, 78.95, 76.04, 'ABOVE'),
(325, '2016-01-11', 82.40, 73.65, 81.34, 75.47, 'ABOVE'),
(324, '2016-01-08', 78.75, 73.40, 77.20, 74.47, 'ABOVE'),
(323, '2016-01-07', 76.40, 72.29, 72.95, 73.74, 'BELOW'),
(322, '2016-01-06', 81.25, 77.70, 78.34, 73.12, 'ABOVE'),
(321, '2016-01-05', 81.75, 76.34, 80.54, 72.08, 'ABOVE'),
(320, '2016-01-04', 80.95, 75.15, 76.29, 70.86, 'ABOVE');

<强>查询

更好地了解它的工作原理，检查每个CTE的结果。

CTE_RowNumbers计算两个行号序列。

CTE_Groups为每个组分配一个号码（上/下）。

CTE_MinMax为每个小组计算MIN/MAX。

最终SELECT选择MIN或MAX返回。

WITH
CTE_RowNumbers
AS
(
    SELECT [Id], [dt], [Val_A], [Val_B], [Val_C], [Avg], [Vector]
        ,ROW_NUMBER() OVER (ORDER BY ID DESC) AS rn1
        ,ROW_NUMBER() OVER (PARTITION BY Vector ORDER BY ID DESC) AS rn2
    FROM @T
)
,CTE_Groups
AS
(
    SELECT [Id], [dt], [Val_A], [Val_B], [Val_C], [Avg], [Vector]
        ,rn1-rn2 AS Groups
    FROM CTE_RowNumbers
)
,CTE_MinMax
AS
(
    SELECT [Id], [dt], [Val_A], [Val_B], [Val_C], [Avg], [Vector]
        ,MAX(Val_A) OVER(PARTITION BY Groups) AS MaxA
        ,MIN(Val_B) OVER(PARTITION BY Groups) AS MinB
    FROM CTE_Groups
)
SELECT [Id], [dt], [Val_A], [Val_B], [Val_C], [Avg], [Vector]
    ,CASE 
        WHEN [Vector] = 'BELOW' THEN MinB
        WHEN [Vector] = 'ABOVE' THEN MaxA
    END AS MINMAXPOINTS
FROM CTE_MinMax
ORDER BY ID DESC;

<强>结果

+-----+------------+-------+-------+-------+-------+--------+--------------+
| Id  |     dt     | Val_A | Val_B | Val_C |  Avg  | Vector | MINMAXPOINTS |
+-----+------------+-------+-------+-------+-------+--------+--------------+
| 329 | 2016-01-15 | 78.09 | 68.4  | 70.29 | 76.5  | BELOW  | 68.4         |
| 328 | 2016-01-14 | 79.79 | 75.4  | 76.65 | 76.67 | BELOW  | 68.4         |
| 327 | 2016-01-13 | 81.15 | 74.59 | 79    | 76.44 | ABOVE  | 82.4         |
| 326 | 2016-01-12 | 81.95 | 77.04 | 78.95 | 76.04 | ABOVE  | 82.4         |
| 325 | 2016-01-11 | 82.4  | 73.65 | 81.34 | 75.47 | ABOVE  | 82.4         |
| 324 | 2016-01-08 | 78.75 | 73.4  | 77.2  | 74.47 | ABOVE  | 82.4         |
| 323 | 2016-01-07 | 76.4  | 72.29 | 72.95 | 73.74 | BELOW  | 72.29        |
| 322 | 2016-01-06 | 81.25 | 77.7  | 78.34 | 73.12 | ABOVE  | 81.75        |
| 321 | 2016-01-05 | 81.75 | 76.34 | 80.54 | 72.08 | ABOVE  | 81.75        |
| 320 | 2016-01-04 | 80.95 | 75.15 | 76.29 | 70.86 | ABOVE  | 81.75        |
+-----+------------+-------+-------+-------+-------+--------+--------------+

Answer 2

您可以使用以下查询使用案例陈述，您可以根据每行的向量值选择条件值。

查询

SELECT ID, DATE, VAL_A, VAL_B, VAL_C, AVG, VECTOR, 
CASE
    WHEN VECTOR = 'BELOW' THEN (SELECT MIN(VAL_B) FROM TABLE A)
    WHEN VECTOR = 'ABOVE' THEN (SELECT MAX(VAL_A) FROM TABLE A)
END AS MINMAXVALUE
FROM TABLE B
GO

检查这是否对您有帮助。

Answer 3

修改查询以检查大于当前记录的数据组您可以使用以下查询使用案例陈述，您可以根据每行的矢量值选择条件值。

查询

SELECT ID, DATE, VAL_A, VAL_B, VAL_C, AVG, VECTOR,
  CASE
    WHEN VECTOR = 'BELOW' THEN (SELECT MIN(VAL_B) FROM TABLE A WHERE ROWID >= B.ROWID)
    WHEN VECTOR = 'ABOVE' THEN (SELECT MAX(VAL_A) FROM TABLE A WHERE ROWID >= B.ROWID)
   END AS MINMAXVALUE

FROM TABLE B 
GO

检查这应该产生您期望从数据中获得的结果。

如何计算SQL Server中序列中组的最小值和最大值？

3 个答案: