Oracle的數據表中行轉列與列轉行的操作實例講解，中行實例講解

Oracle的數據表中行轉列與列轉行的操作實例講解，中行實例講解

行轉列
一張表

查詢結果為

--行轉列

select years,(select amount from Tb_Amount as A where month=1 and A.years=Tb_Amount.years)as m1,
(select amount from Tb_Amount as A where month=2 and A.years=Tb_Amount.years)as m2,
(select amount from Tb_Amount as A where month=3 and A.years=Tb_Amount.years)as m3
from Tb_Amount group by years

或者為

select years as 年份,
sum(case when month='1' then amount end) as 一月,
 sum(case when month='2' then amount end) as 二月,
sum(case when month='3' then amount end) as 三月
from dbo.Tb_Amount group by years order by years desc

2.人員信息表包括姓名 時代  金額

顯示行轉列
姓名     時代       金額

姓名  年輕         中年       老年

張麗 1000000.00 4000000.00    500000000.00

孫子 2000000.00   12233335.00  4552220010.00

select uname as 姓名,
SUM(case when era='年輕' then amount end) as 年輕,
SUM(case when era='中年' then amount end) as 中年,
SUM(case when era='老年' then amount end) as 老年
from Tb_People group by uname order by uname desc

 3.學生表 [Tb_Student]

顯示效果

靜態SQL,指subject只有語文、數學、英語這三門課程。

select sname as 姓名,
max(case Subject when '語文' then grade else 0 end) as 語文,
max(case Subject when '數學' then grade else 0 end) as 數學,
max(case Subject when '英語' then grade else 0 end) as 英語
from dbo.Tb_Student group by sname order by sname desc

--動態SQL,指subject不止語文、數學、英語這三門課程。

declare @sql varchar(8000)
set @sql = 'select sname as ' + '姓名'
select @sql = @sql + ' , max(case Subject when ''' + Subject + ''' then grade else 0 end) [' + Subject + ']'
from (select distinct Subject from Tb_Student) as a
set @sql = @sql + ' from Tb_Student group by sname order by sname desc'
exec(@sql)

oracle中Decode()函數使用 然後將這些累計求和(sum部分）

select t.sname AS 姓名,
sum(decode(t.subject,'語文',grade,null))語文 ,
sum(decode(t.subject,'數學',grade,null)) 數學,
sum(decode(t.subject,'英語',grade,null)) 英語
from Tb_Student t group by sname order by sname desc

列轉行

生成

sql代碼
生成靜態:

select *
from (select sname,[Course ] ='數學',[Score]=[數學] from Tb_students union all
select sname,[Course]='英語',[Score]=[英語] from Tb_students union all
select sname,[Course]='語文',[Score]=[語文] from Tb_students)t
order by sname,case [Course] when '語文' then 1 when '數學' then 2 when '英語' then 3 end
go
 --列轉行的靜態方案：UNPIVOT,sql2005及以後版本
 
 SELECT sname,Subject, grade
 from dbo.Tb_students
 unpivot(grade for Subject in([語文],[數學],[英語]))as up
 GO
 
 
 --列轉行的動態方案：UNPIVOT,sql2005及以後版本
 --因為行是動態所以這裡就從INFORMATION_SCHEMA.COLUMNS視圖中獲取列來構造行，同樣也使用了XML處理。
 declare @s nvarchar(4000)
select @s=isnull(@s+',','')+quotename(Name)
from syscolumns where ID=object_id('Tb_students') and Name not in('sname')
order by Colid
exec('select sname,[Subject],[grade] from Tb_students unpivot ([grade] for [Subject] in('+@s+'))b')

go
select
  sname,[Subject],[grade]
from
  Tb_students
unpivot
  ([grade] for [Subject] in([數學],[英語],[語文]))b

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