[英]How to pivot rows into columns (custom pivoting)
我有一个类似于以下的Sql Database表:
Day Period Subject
Mon 1 Ch
Mon 2 Ph
Mon 3 Mth
Mon 4 CS
Mon 5 Lab1
Mon 6 Lab2
Mon 7 Lab3
Tue 1 Ph
Tue 2 Ele
Tue 3 Hu
Tue 4 Ph
Tue 5 En
Tue 6 CS2
Tue 7 Mth
我希望它显示如下:种类的交叉表或枢轴
Day P1 P2 P3 P4 P5 P6 P7
Mon Ch Ph Mth CS2 Lab1 Lab2 Lab3
Tue Ph Ele Hu Ph En CS2 Mth
这样做的理想方式是什么? 有人可以给我看一下Sql代码吗?
您可以使用PIVOT函数来完成它,但我更喜欢旧的学校方法:
SELECT
dy,
MAX(CASE WHEN period = 1 THEN subj ELSE NULL END) AS P1,
MAX(CASE WHEN period = 2 THEN subj ELSE NULL END) AS P2,
MAX(CASE WHEN period = 3 THEN subj ELSE NULL END) AS P3,
MAX(CASE WHEN period = 4 THEN subj ELSE NULL END) AS P4,
MAX(CASE WHEN period = 5 THEN subj ELSE NULL END) AS P5,
MAX(CASE WHEN period = 6 THEN subj ELSE NULL END) AS P6,
MAX(CASE WHEN period = 7 THEN subj ELSE NULL END) AS P7
FROM
Classes
GROUP BY
dy
ORDER BY
CASE dy
WHEN 'Mon' THEN 1
WHEN 'Tue' THEN 2
WHEN 'Wed' THEN 3
WHEN 'Thu' THEN 4
WHEN 'Fri' THEN 5
WHEN 'Sat' THEN 6
WHEN 'Sun' THEN 7
ELSE 8
END
只是因为你想要新的学校方法。 (Pivot语句应该在SQL2005 +中工作, VALUES
位仅用于示例数据SQL2008)
WITH ExampleData AS
(
SELECT X.*
FROM (VALUES
('Mon', 1, 'Ch'),
('Mon', 2, 'Ph'),
('Mon', 3, 'Mth'),
('Mon', 4, 'CS'),
('Mon', 5, 'Lab1'),
('Mon', 6, 'Lab2'),
('Mon', 7, 'Lab3'),
('Tue', 1, 'Ph'),
('Tue', 2, 'Ele'),
('Tue', 3, 'Hu'),
('Tue', 4, 'Ph'),
('Tue', 5, 'En'),
('Tue', 6, 'CS2'),
('Tue', 7, 'Mth')
) AS X (Day, Period, Subject)
)
SELECT Day, [1] AS P1, [2] AS P2,[3] AS P3, [4] AS P4, [5] AS P5,[6] AS P6,[7] AS P7
FROM ExampleData
PIVOT
(
Max(Subject)
FOR Period IN ([1], [2],[3],[4], [5],[6], [7])
) AS PivotTable;
结果
Day P1 P2 P3 P4 P5 P6 P7
---- ---- ---- ---- ---- ---- ---- ----
Mon Ch Ph Mth CS Lab1 Lab2 Lab3
Tue Ph Ele Hu Ph En CS2 Mth
DECLARE @TIMETABLE TABLE (
[Day] CHAR(3),
[Period] TINYINT,
[Subject] CHAR(5)
)
INSERT INTO @TIMETABLE([Day], [Period], [Subject])
VALUES
('Mon', 1, 'Ch'),
('Mon', 2, 'Ph'),
('Mon', 3, 'Mth'),
('Mon', 4, 'CS'),
('Mon', 5, 'Lab1'),
('Mon', 6, 'Lab2'),
('Mon', 7, 'Lab3'),
('Tue', 1, 'Ph'),
('Tue', 2, 'Ele'),
('Tue', 3, 'Hu'),
('Tue', 4, 'Ph'),
('Tue', 5, 'En'),
('Tue', 6, 'CS2'),
('Tue', 7, 'Mth')
SELECT
[Day],
MAX(CASE [Period] WHEN 1 THEN [Subject] END) AS P1,
MAX(CASE [Period] WHEN 2 THEN [Subject] END) AS P2,
MAX(CASE [Period] WHEN 3 THEN [Subject] END) AS P3,
MAX(CASE [Period] WHEN 4 THEN [Subject] END) AS P4,
MAX(CASE [Period] WHEN 5 THEN [Subject] END) AS P5,
MAX(CASE [Period] WHEN 6 THEN [Subject] END) AS P6,
MAX(CASE [Period] WHEN 7 THEN [Subject] END) AS P7
FROM @TIMETABLE
GROUP BY [Day]
你可以试试......
SELECT DISTINCT Day,
(SELECT Subject
FROM my_table mt2
WHERE mt2.Day = mt.Day AND
Period = 1) AS P1,
(SELECT Subject
FROM my_table mt2
WHERE mt2.Day = mt.Day AND
Period = 2) AS P2,
.
.
etc
.
.
.
(SELECT Subject
FROM my_table mt2
WHERE mt2.Day = mt.Day AND
Period = 7) AS P7
FROM my_table mt;
但我不能说我非常喜欢它。 但总比没有好。
使用交叉应用以单个列中的逗号分隔格式获取所有值。 而不是“7”不同的列。 以下查询可用于任何列 - >行映射
SELECT DISTINCT Day, [DerivedColumn] FROM <Table> A CROSS APPLY ( SELECT Period + ',' FROM <Table> B WHERE A.Day = B.Day Order By Period FOR XML PATH('') ) AS C (DerivedColumn)
您可以在Mon的一列中获得[Ch,Ph,Mth,CS2,Lab1,Lab2,Lab3]等等......您可以将其用作查询任何特定日期的表格。
希望这可以帮助
with pivot_data as
(
select [day], -- groping column
period, -- spreading column
subject -- aggreate column
from pivot_tb
)
select [day], [1] AS P1, [2] AS P2,[3] AS P3, [4] AS P4, [5] AS P5,[6] AS P6,[7] AS P7
from pivot_data
pivot ( max(subject) for period in ([1], [2],[3],[4], [5],[6], [7]) ) as p;
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