python数据逆透视_PIVOT(透视转换)和UNPIVOT(逆透视转换)

一、原数据状态

二、手动写透视转换1

三、手动写透视转换2

四、PIVOT(透视转换)和UNPIVOT(逆透视转换)详细使用

使用标准SQL进行透视转换和逆视转换

--行列转换

create table#demoOrders

(

idint primary key identity(1,1),

CompanyNamenvarchar(50),

ProductIDint,

ProductNamenvarchar(50)

)insert into #demoOrders (CompanyName,ProductID,ProductName) values('公司1','1','产品1')insert into #demoOrders (CompanyName,ProductID,ProductName) values('公司1','2','产品2')insert into #demoOrders (CompanyName,ProductID,ProductName) values('公司2','2','产品2')insert into #demoOrders (CompanyName,ProductID,ProductName) values('公司2','3','产品3')insert into #demoOrders (CompanyName,ProductID,ProductName) values('公司3','3','产品3')insert into #demoOrders (CompanyName,ProductID,ProductName) values('公司4','3','产品3')insert into #demoOrders (CompanyName,ProductID,ProductName) values('公司5','4','产品4')insert into #demoOrders (CompanyName,ProductID,ProductName) values('公司6','4','产品4')insert into #demoOrders (CompanyName,ProductID,ProductName) values('公司6','5','产品5')select * from #demoOrders

透视转换的标准SQL解决方案以一种非常直接的方式来处理转换过程中涉及的三个阶段：

1、分组阶段用group by 子句实现

2、扩展阶段通过在select子句中为每个目标列指定case表达式来实现，这需要事先知道每个扩展元素的取值，并为每个值指定一个单独的case表达式。

3、聚合阶段通过为每个case表达式的结果应用相关的聚合函数来实现。

解题思维步骤：

1.先找到为行列转换的数据，分组查看数据试试：

select CompanyName,ProductName,count(*) as num from#demoOrdersgroup by ProductName,CompanyName order by CompanyName

2.分组阶段:用group by 子句以行作为分组条件,获取行数据

selectCompanyNamefrom(select CompanyName,ProductName,COUNT(*)as num from #demoOrders group byProductName,CompanyName

) Tgroup by CompanyName

3.扩展阶段:找到列的数据,为每个目标列指定case表达式;聚合阶段通过为每个case表达式的结果应用相关的聚合函数来实现

selectCompanyName,sum(case when ProductName='产品1' then num else 0 end)[产品1],sum(case when ProductName='产品2' then num else 0 end)[产品2],sum(case when ProductName='产品3' then num else 0 end)[产品3],sum(case when ProductName='产品4' then num else 0 end)[产品4],sum(case when ProductName='产品5' then num else 0 end)[产品5]

from(select CompanyName,ProductName,COUNT(*)as num from #demoOrders group byProductName,CompanyName

) Tgroup byCompanyName--以下是分页存储过程，看看拼接sql语句字符串和执行的过程，然后把思路打开一下试试

declare @sql nvarchar(1000)set @sql='select CompanyName,'--开始设置语句--------动态生成语句begin(开始转成列)-----

select @sql=@sql+'sum(case when ProductName='''+ProductName+'''then num else 0 end)['+ProductName+'],'

from (select distinct top 100 percent ProductName from #demoOrders order byProductName)a--------动态生成语句 end--------------------

print @sql

set @sql =left(@sql,len(@sql)-1)+'from (select CompanyName,ProductName,COUNT(*)as num from #demoOrders group by ProductName,CompanyName)a group by CompanyName'

print @sql --打印输出最终执行的SQL

exec(@sql) --执行SQL字符串

逆透视转换的标准SQL解决方案要实现三个逻辑处理阶段：

1、生成副本：根据来源表的每一行生成多个副本(为需要逆透视的每个列生成一个副本)；用cross join(交叉联接)来生成每一行的多个副本

2、提取元素

3、删除不相关的交叉

--逆视数据

selectCompanyName,sum(case when ProductName='产品1' then num else 0 end)[产品1],sum(case when ProductName='产品2' then num else 0 end)[产品2],sum(case when ProductName='产品3' then num else 0 end)[产品3],sum(case when ProductName='产品4' then num else 0 end)[产品4],sum(case when ProductName='产品5' then num else 0 end)[产品5]

into#unpivotDemofrom(select CompanyName,ProductName,COUNT(*)as num from #demoOrders group byProductName,CompanyName

) agroup by CompanyName

1、在#unpivotDemo表和每行ProductName之间进行交叉联接

select * from#unpivotDemocross join(values('产品1'),('产品2'),('产品3'),('产品4'),('产品5')) as#unpivotDemo2(ProductName)--或：

select * from#unpivotDemocross join(select '产品1' asProductNameunion all

select '产品2'

union all

select '产品3'

union all

select '产品4'

union all

select '产品5')as #unpivotDemo2

2.1、生成一个数据列，由它返回与当前副本所代表的产品相对应的列值

select *,caseProductNamewhen '产品1' then产品1when '产品2' then产品2when '产品3' then产品3when '产品4' then产品4when '产品5' then产品5end asnumfrom#unpivotDemocross join (values('产品1'),('产品2'),('产品3'),('产品4'),('产品5')) as#unpivotDemo2(ProductName)--或：

select *,caseProductNamewhen '产品1' then产品1when '产品2' then产品2when '产品3' then产品3when '产品4' then产品4when '产品5' then产品5end asnumfrom#unpivotDemocross join(select '产品1' asProductNameunion all

select '产品2'

union all

select '产品3'

union all

select '产品4'

union all

select '产品5')as #unpivotDemo2

2.2、提取所需的数据列

selectCompanyName,ProductName,caseProductNamewhen '产品1' then产品1when '产品2' then产品2when '产品3' then产品3when '产品4' then产品4when '产品5' then产品5end asnumfrom#unpivotDemocross join (values('产品1'),('产品2'),('产品3'),('产品4'),('产品5')) as#unpivotDemo2(ProductName)--或：

selectCompanyName,ProductName,caseProductNamewhen '产品1' then产品1when '产品2' then产品2when '产品3' then产品3when '产品4' then产品4when '产品5' then产品5end asnumfrom#unpivotDemocross join(select '产品1' asProductNameunion all

select '产品2'

union all

select '产品3'

union all

select '产品4'

union all

select '产品5')as #unpivotDemo2

3、0值与NULL值代表不相关的交叉，为了删除不相关的交叉，在外部查询中过滤掉0值与NULL值

select * from(selectCompanyName,ProductName,caseProductNamewhen '产品1' then产品1when '产品2' then产品2when '产品3' then产品3when '产品4' then产品4when '产品5' then产品5end asnumfrom#unpivotDemocross join (values('产品1'),('产品2'),('产品3'),('产品4'),('产品5')) as#unpivotDemo2(ProductName)

)asTwhere num is not null and num <> 0

--或：

select * from(selectCompanyName,ProductName,caseProductNamewhen '产品1' then产品1when '产品2' then产品2when '产品3' then产品3when '产品4' then产品4when '产品5' then产品5end asnumfrom#unpivotDemocross join(select '产品1' asProductNameunion all

select '产品2'

union all

select '产品3'

union all

select '产品4'

union all

select '产品5')as#unpivotDemo2

)asTwhere num is not null and num <> 0

使用T-SQL PIVOT透视转换和UNPIVOT逆透视转换

pivot的使用

select CompanyName,[产品1] as 产品1,[产品2] as 产品2,[产品3] as 产品3,[产品4] as 产品4,[产品5] as产品5from(--表表达式作为pivot输入表,仅仅返回透视中用到的列

select CompanyName,ProductName,count(*) as num from#demoOrdersgroup byProductName,CompanyName

)as sourceTable --分组是隐含的，对表中除掉聚合和条件的列进行分组

pivot

(sum(num) --聚合函数

for ProductName in([产品1],[产品2],[产品3],[产品4],[产品5]) --准备做列名

) as PivotTable

create table#demotable

(

idint primary key identity(1,1),

orderMonthint,

subTotaldecimal(18,2)

)insert into #demotable (orderMonth,subTotal) values(5,100.00)insert into #demotable (orderMonth,subTotal) values(6,100.00)insert into #demotable (orderMonth,subTotal) values(5,200.00)insert into #demotable (orderMonth,subTotal) values(6,200.00)insert into #demotable (orderMonth,subTotal) values(7,100.00)select * from#demotable--方式一

select id,[5] as 五月,[6] as 六月,[7] as七月from#demotable--基础表作为pivot输入表

pivot

(sum(#demotable.subTotal) for #demotable.orderMonth in([5],[6],[7])

)asPivotTable--方式二(推荐使用表表达式作为pivot的输入表，不要对基础表进行操作)：

select id,[5] as 五月,[6] as 六月,[7] as七月from(--表表达式作为pivot输入表,仅仅返回透视中用到的列

select id,orderMonth,subTotal from#demotable

)as sourceTable --分组是隐含的，对表中除掉聚合和条件的列进行分组

pivot

(sum(subTotal) --聚合函数

for orderMonth in([5],[6],[7]) --准备做列名

) asPivotTabledrop table #demotable

unpivot的使用

create table#demotable2

(

idint,

五月int,

六月int,

七月int)insert into #demotable2 values (1,100,100,0);insert into #demotable2 values (2,200,200,200);insert into #demotable2 values (3,800,0,0);select * from#demotable2--执行UNPIVOT

selectid,orderMonth,subTotalFROM#demotable2

unpivot

(

subTotalfor orderMonth in(五月,六月,七月)

)ASUnpivotTabledrop table #demotable2

练习：

create table#testtable

(

idint primary key identity(1,1),

t_yearint,

t_monthint,

t_amountdecimal(18,1)

)insert into #testtable (t_year,t_month,t_amount) values(1991,1,1.1)insert into #testtable (t_year,t_month,t_amount) values(1991,2,1.2)insert into #testtable (t_year,t_month,t_amount) values(1991,3,1.3)insert into #testtable (t_year,t_month,t_amount) values(1992,1,2.1)insert into #testtable (t_year,t_month,t_amount) values(1992,2,2.2)insert into #testtable (t_year,t_month,t_amount) values(1992,3,2.3)--drop table #testtable

select * from#testtable--//想要的结果--year m1 m2 m3--1991 1.1 1.2 1.3--1992 2.1 2.2 2.3

select max(t_year) as [year],max([1]) as m1,max([2]) as m2,max([3]) asm3from#testtable

pivot

(max(t_amount) for t_month in([1],[2],[3])

)asPivotTablegroup byt_yearselectt_amount,ColumnName,YearAndMonthfrom#testtable

unpivot

(

YearAndMonthfor ColumnName in(t_year,t_month)

)asUnpivotTable--行列转换--解题思维步骤：--1.先找到为行列转换的数据，查看数据试试：

select t_year,t_month,t_amount from#testtable--2.找到列的数据

select(case when t_month=1 then t_amount else 0 end)[m1],

(case when t_month=2 then t_amount else 0 end)[m2],

(case when t_month=3 then t_amount else 0 end)[m3]

from#testtable--3.以行作为分组条件,获取行数据;两者结合起来，答案：

selectt_year,max(case when t_month=1 then t_amount else 0 end)[m1],max(case when t_month=2 then t_amount else 0 end)[m2],max(case when t_month=3 then t_amount else 0 end)[m3]

from#testtablegroup byt_year--------------------以下是sql语句字符串和执行的过程------------------------

declare @sql nvarchar(1000)set @sql='select t_year,'

--------动态生成列 begin--------

select @sql=@sql+'max(case when t_month='+convert(nvarchar(20),t_month)+'then t_amount else 0 end)[m'+str(t_month,1)+'],'

from (select distinct top 100 percent t_month from #testtable order byt_month) Tprint @sql

--------动态生成列 end--------

set @sql=left(@sql,len(@sql)-1)+'from #testtable group by t_year'

print @sql

exec(@sql)