使用动态SQL语句进行数据透视 [英] Pivot using Dynamic SQL statement

问题描述

这是数据的一小部分.在实际数据中，名称"和代码"下的值有数百个，并且这些值经常更改. 因此，对Pivot语句进行硬编码将不起作用.需要创建一个动态SQL语句-我需要帮助.

This is a small sample of the data. In the actual data, the values under Name and Code are in the hundreds and those values change frequently. For this reason, hard-coding the Pivot statement will not work. There needs to be a dynamic SQL statement created - and I need help with that.

DECLARE @Test Table
(
  Name   Varchar(32),
  Code   Varchar(20)
)

INSERT INTO @Test(Name, Code) VALUES
  ('A-1', 'A-One')
, ('A 2', 'A-Two')
, ('B 1-b', 'B-One')
, ('B', 'A-Two')
, ('C', 'A-One')
, ('C', 'B-One')
, ('C', 'C-One')

样本数据集看起来像这样[同样，这只是一个小样本]:

The sample data set looks like this [again, this is just a small sample]:

Name    Code
A-1     A-One
A 1     A-Two
B 1-b   B-One
B       A-Two 
C       A-One
C       B-One
C       C-One

请注意，代码"值(例如A-One，A-Two和B-One)可能与一个以上的Name值相关联.

Notice that Code values [like A-One, A-Two, and B-One] may be associated with more than one Name value.

例如A-One出现，名称为A-1，以及名称C ...

E.g. A-One appears with Name A-1, as well as Name C ...

我想输出它，使它看起来像这样[除了，比我显示的值多得多-这些值可以更改]:

I want to output it so it looks like this [except, with a lot more values than I am showing - and those values can change]:

             A-1      A 1        B 1-b          B      C
A-One        X                                         X
A-Two                  X                        X   
B-One                             X                    X
C-One                                                  X

名称"值和代码"值的数量可以更改.它们不是恒定的.

The number of 'Name' values and Code values can change. They are not constant.

目标是能够查看左侧的Code值列表-并轻松查看与Codes关联的Name值.

The goal is to be able to look down the list of Code values on the left - and easily see which Name values the Codes are associated with.

我相信这需要创建动态透视图sql，并且在理解Pivot sql时遇到问题，我将不胜感激任何帮助或指针.

I believe this requires dynamic pivot sql to be created and I have trouble understanding Pivot sql and I would appreciate any help or pointers.

推荐答案

您可以使用动态数据透视表:

You can use a dynamic pivot:

create table dbo.test([Name] Varchar(32), Code Varchar(30)) 

insert into dbo.test values 
  ('A-1', 'A-One')
, ('A 2', 'A-Two')
, ('B 1-b', 'B-One')
, ('B', 'A-Two')
, ('C', 'A-One')
, ('C', 'B-One')
, ('C', 'C-One')

declare @cols nvarchar(max)=''  --holds all the values that will become column names 
declare @alias nvarchar(max)='' --holds values that will become column names and converts values to 'x'
declare @sql nvarchar(max)=''   --contains the TSQL dinamically generated 

select @cols = @cols + ', [' + [Name] + ']' 
from dbo.test 
group by [Name] 

select @alias = @alias + ', case when T.[' + [Name] + '] is not null then ''x'' else '''' end as [' + [Name] + ']'
from dbo.test 
group by [Name] 

set @cols = RIGHT(@cols, len(@cols)-2) 
set @sql = @sql + ' select  T.Code ' + @alias + ' from ('
set @sql = @sql + ' select piv.[Code], ' + @cols 
set @sql = @sql + ' from dbo.test ' 
set @sql = @sql + ' pivot (max([Name]) for [Name] in ('+@cols+') ) piv ' 
set @sql = @sql + ' ) T' 

--execute dynamic query
exec(@sql)

结果:

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