我如何表列轉換爲行

Question

有一個表，如下圖所示：

+-----------+------------+--------+ 
| Col1 | Col2 | Col3 | 
+-----------+------------+--------+ 
| 12345678 | FirstName | John | 
| 12345678 | LastName | Smith | 
| 987456321 | LastName | Clancy | 
| 987456321 | MiddleName | T  | 
| 987456321 | Height  | 176cm | 
| 654125878 | FirstName | Tan | 
| 654125878 | Weight  | 150lb | 
+-----------+------------+--------+

如何將其轉換成：

 
+-----------+-----------+------------+----------+--------+--------+ 
| ID  | FirstName | MiddleName | LastName | Height | Weight | 
+-----------+-----------+------------+----------+--------+--------+ 
| 12345678 | John  | null  | Smith | null | null | 
| 987456321 | null  | T   | Clancy | 176cm | null | 
| 654125878 | Tan  | null  | null  | null | 150lb | 
+-----------+-----------+------------+----------+--------+--------+

Answer 1

我認爲有條件的聚集會在這裏做的伎倆。

假設你不需要動態

Select ID = Col1 
     ,FirstName = max(case when Col2='FirstName' then Col3 else null end) 
     ,MiddleName = max(case when Col2='MiddleName ' then Col3 else null end) 
     ,LastName = max(case when Col2='LastName ' then Col3 else null end) 
     ,Height  = max(case when Col2='Height'  then Col3 else null end) 
     ,Weight  = max(case when Col2='Weight'  then Col3 else null end) 
From YourTable 
Group By Col1 

如果你需要動態

Declare @SQL varchar(max) = Stuff((Select Distinct ',' + QuoteName([Col2]) From Yourtable Order by 1 For XML Path('')),1,1,'') 
Select @SQL = ' 
Select [Col1] as ID ,' + @SQL + ' 
From YourTable 
Pivot (max(Col3) For [Col2] in (' + @SQL + ')) p' 
Exec(@SQL); 

如果有幫助，對於動態透視生成的SQL如下：

Select [Col1] as ID ,[FirstName],[Height],[LastName],[MiddleName],[Weight] 
From YourTable 
Pivot (max(Col3) For [Col2] in ([FirstName],[Height],[LastName],[MiddleName],[Weight])) p