行列转换的例子

Posted 2020-09-25 Energy

IF OBJECT_ID(‘tempdb..#ABC‘) IS NOT NULL  
DROP TABLE #ABC  
  
create table #ABC  
(  
ID  INT  
,UserID BIGINT    
,UserExamID INT   
,TestPaperID INT      
,QuestionID INT  
,AnswerID   INT  
,Ctime DATETIME  
)  
INSERT INTO #ABC  
SELECT 1,120629210042331600,1,3,22,49,GETDATE() UNION ALL  
SELECT 2,120629210042331600,1,3,23,51,GETDATE() UNION ALL  
SELECT 3,120629210042331600,1,3,24,56,GETDATE() UNION ALL  
SELECT 4,120629210042331600,1,3,25,62,GETDATE() UNION ALL  
SELECT 5,120629210042331600,1,3,26,66,GETDATE() UNION ALL  
SELECT 6,120629210042331600,1,3,27,72,GETDATE() UNION ALL  
SELECT 7,120629210042331600,1,3,28,77,GETDATE() UNION ALL  
SELECT 8,120629210042331600,1,3,29,81,GETDATE() UNION ALL  
SELECT 9,120629210042331600,1,3,30,86,GETDATE() UNION ALL  
SELECT 10,120629210042331600,1,3,31,90,GETDATE() UNION ALL  
SELECT 1,120629210011732588,1,3,22,49,GETDATE() UNION ALL  
SELECT 2,120629210011732588,1,3,23,51,GETDATE() UNION ALL  
SELECT 3,120629210011732588,1,3,24,56,GETDATE() UNION ALL  
SELECT 4,120629210011732588,1,3,25,62,GETDATE() UNION ALL  
SELECT 5,120629210011732588,1,3,26,66,GETDATE() UNION ALL  
SELECT 6,120629210011732588,1,3,27,72,GETDATE() UNION ALL  
SELECT 7,120629210011732588,1,3,28,77,GETDATE() UNION ALL  
SELECT 8,120629210011732588,1,3,29,81,GETDATE() UNION ALL  
SELECT 9,120629210011732588,1,3,30,86,GETDATE() UNION ALL  
SELECT 10,120629210011732588,1,3,31,90,GETDATE()    
  
SELECT * FROM #ABC  


DECLARE @s NVARCHAR(4000)  
SELECT @s = ISNULL(@s + ‘,‘, ‘‘) +  QUOTENAME(QuestionID)  
FROM  (select distinct QuestionID from #ABC) as A ---列名不要重复  
  
Declare @sql NVARCHAR(4000)  
SET @sql=‘  
 select r.* from  
(select UserID,QuestionID,AnswerID from #ABC) as t  
pivot  
(  
max(t.AnswerID)  
for t.QuestionID in (‘+@s+‘)  
) as r‘  
   
EXEC( @sql) 

如果要消除NULL，可以利用@s构造一个 ISNULL(字段.0) AS [字段]