[英]How to pivot rows into columns (custom pivoting)
I have a Sql Database table similar to the following: 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
I would like it displayed as follows: Kind of crosstab or Pivot 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
What would be the ideal way to do it? 这样做的理想方式是什么? Can someone please show me the Sql code please?
有人可以给我看一下Sql代码吗?
You could probably do it with the PIVOT function, but I prefer the old school method: 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
Just incase you do want the new school method. 只是因为你想要新的学校方法。 (The Pivot statement should work in SQL2005+, the
VALUES
bit for the example data only SQL2008) (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;
Result 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]
You could try... 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;
but I can't say I like it very much. 但我不能说我非常喜欢它。 Better than nothing, though.
但总比没有好。
Use cross apply to get all the values in a comma delimted format in a single column. 使用交叉应用以单个列中的逗号分隔格式获取所有值。 instead of "7" different columns.
而不是“7”不同的列。 The following query can be used for any column-> row mapping
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)
You will get [Ch,Ph,Mth,CS2,Lab1,Lab2,Lab3] in one column for Mon and so on ... You could use this as a table to query for any particular Day. 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。
Hope this helps 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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