數據透視所需的幫助（SQL Server 2005）

Question

我有一張桌子

ID  Grps    Vals
--- ----    -----
1   1   1
1   1   3
1   1   45
1   2   23
1   2   34
1   2   66
1   3   10
1   3   17
1   3   77
2   1   144
2   1   344
2   1   555
2   2   11
2   2   22
2   2   33
2   3   55
2   3   67
2   3   77

所需的輸出是

ID  Record1     Record2     Record3
--- -------     -------     -------
1   1       23      10      
1   3       34      17      
1   45      66      77
2   144     11      55
2   344     22      67
2   555     33      77

我已經嘗試過（使用while循環），但是程序運行緩慢。 我被要求通過使用基於SET的方法來這樣做。 到目前為止，我的方法是

SELECT  ID,[1] AS [Record1], [2] AS [Record2], [3] as [Record3]
    FROM (  
    Select 
        Row_Number() Over(Partition By ID Order By Vals) records
        ,* 
        From myTable)x
    PIVOT
  (MAX(vals) FOR Grps IN ([1],[2],[3])) p

但這是行不通的。

任何人都可以幫助解決此問題。（SQL SERVER 2005）

Answer 1

你快到了！ 我要做的就是將必要的列添加到Partition By和Order By子句中，並且可以正常工作：

SELECT  ID,[1] AS [Record1], [2] AS [Record2], [3] as [Record3] 
    FROM (   
    Select  
        Row_Number() Over(Partition By id, grps Order By id, grps, vals) records 
        ,*  
        From myTable)x 
    PIVOT 
  (MAX(vals) FOR Grps IN ([1],[2],[3])) p 

Answer 2

一個不涉及使用PIVOT的簡單方法將是：

;With ItemGroups As
    (
    Select Id, Grps, Vals 
        , Row_Number() Over ( Partition By Id, Grps Order By Vals ) As RowNum
    From myTable
    )
Select Id
    , Max( Case When Grps = 1 Then Vals End )
    , Max( Case When Grps = 2 Then Vals End )
    , Max( Case When Grps = 3 Then Vals End )
From ItemGroups
Group By Id, RowNum
Order By Id

Answer 3

這可能不適用於您，但是如果您使用while循環之類的話...

while( x<Total.length() ){
....do something
}

you should declare Total.length outside of the loop assigned to a variable...

int spoon= Total.length();
while( x< spoon ){
....do something
}

要不然

您每次循環運行時都會計算總數Total.length（）