Transpose Row to Column in SQL Server 2000

Question

我想将行转换为SQL Server 2000中的列。尽管所有行都转换为所需的列，但我无法将值转换为相应的列。

我的代码是：

DROP TABLE prePivot1 
DROP TABLE results1 

CREATE TABLE prePivot1 (
    [StudentId] uniqueidentifier 
    , [Sub_Abbr] Varchar(100) 
    , [Total_marks] MONEY 
    ) 

CREATE TABLE results1 (
    [StudentId] uniqueidentifier 
    ) 

INSERT INTO prePivot1 
SELECT  '{4FD7CBBA-1621-4102-B4A3-000BF92E2F6E}', 'ENG', 55 
UNION SELECT '{4FD7CBBA-1621-4102-B4A3-000BF92E2F6E}', 'MBEN', 90 
UNION SELECT '{4FD7CBBA-1621-4102-B4A3-000BF92E2F6E}', 'ECO', 80 
UNION SELECT '{4FD7CBBA-1621-4102-B4A3-000BF92E2F6E}', 'PSc', 45 
UNION SELECT '{4FD7CBBA-1621-4102-B4A3-000BF92E2F6E}', 'PSY', 23 

UNION SELECT '{AD288712-5C97-446B-8AFE-003FC845B56B}', 'ENG', 90 
UNION SELECT '{AD288712-5C97-446B-8AFE-003FC845B56B}', 'ECO', 44 
UNION SELECT '{AD288712-5C97-446B-8AFE-003FC845B56B}', 'PSc', 45 
UNION SELECT '{AD288712-5C97-446B-8AFE-003FC845B56B}', 'BST', 23 
UNION SELECT '{AD288712-5C97-446B-8AFE-003FC845B56B}', 'ASS', 80 
UNION SELECT '{AD288712-5C97-446B-8AFE-003FC845B56B}', 'PSY', 93 




DECLARE @sql VARCHAR(8000) 
DECLARE @pivot varchar(10) 

DECLARE pivotCursor CURSOR LOCAL READ_ONLY FOR 
SELECT DISTINCT 
    [Sub_abbr] 
FROM 
    prePivot1 

OPEN pivotCursor 
    FETCH NEXT FROM pivotCursor INTO @pivot 

    WHILE (@@FETCH_STATUS = 0) BEGIN 

     SET @sql = ' 
     ALTER TABLE results1 ADD [' + CAST(@pivot AS VARCHAR(10)) + '] INT' 
     EXEC (@sql) 

     FETCH NEXT FROM pivotCursor INTO @pivot 
    END 
CLOSE pivotCursor 

INSERT INTO results1 ([studentId]) 
SELECT DISTINCT [StudentId] FROM prePivot1 

OPEN pivotCursor 
    FETCH NEXT FROM pivotCursor INTO @pivot 

    WHILE (@@FETCH_STATUS = 0) BEGIN 

     SET @sql = ' 
     UPDATE results1 
     SET 
      [' + CAST(@pivot AS VARCHAR(10)) + '] = pp.[total_marks] 
     FROM 
      prePivot1 pp 
     WHERE 
      pp.[total_marks] = ' + CAST(@pivot AS VARCHAR(10)) + ' 
      AND pp.[studentId] = results1.[studentId]' 

     EXEC (@sql) 

     FETCH NEXT FROM pivotCursor INTO @pivot 
    END 
CLOSE pivotCursor 
DEALLOCATE pivotCursor 

SELECT * FROM results1 

请帮助我我该怎么做，以获得预期的结果。 提前感谢您。

Answer 1

有几件事情错了你的断言在这里：

pp.[total_marks] = ' + CAST(@pivot AS VARCHAR(10)) + ' 

1. 你是在错误的列
2. 你是不是产生与@pivot部分正确的字符串过滤。

这就是您打印出动态sql字符串时的样子。请注意，它会导致prePivot1.total_marks列上的连接到results1.ECO列，这不是您想要的。

UPDATE 
    results1 
SET 
    [ECO] = pp.[total_marks] 
FROM 
    prePivot1 AS pp 
WHERE 
    pp.[total_marks] = ECO 
    AND pp.[studentId] = results1.[studentId] 

修改后的版本（你也不需要转换的变量）：

pp.[Sub_Abbr] = ''' + @pivot + ''' 

稍微不容易出错的解决办法是参数化动态SQL：

-- Change @sql --> nvarchar(4000)  
SET @sql = N' 
UPDATE 
    results1 
SET 
    ' + QUOTENAME(@pivot) + N' = pp.[total_marks] 
FROM 
    prePivot1 AS pp 
WHERE 
    pp.[Sub_Abbr] = @Sub_Abbr 
    AND pp.[studentId] = results1.[studentId];'; 

EXEC sp_executesql 
    @stmt = @sql, 
    @params = N'@Sub_Abbr varchar(10)', 
    @Sub_Abbr = @pivot; 

这是我在sql2k中使用的一般模式，仅供参考： （我在这里假设StudentId，Sub_Abbr是唯一的，虽然架构没有明确证实这一点）

SELECT 
    [StudentId], 
    MAX(CASE WHEN [Sub_Abbr] = 'ASS' THEN [Total_marks] ELSE NULL END) AS [ASS], 
    MAX(CASE WHEN [Sub_Abbr] = 'BST' THEN [Total_marks] ELSE NULL END) AS [BST], 
    MAX(CASE WHEN [Sub_Abbr] = 'ECO' THEN [Total_marks] ELSE NULL END) AS [ECO], 
    MAX(CASE WHEN [Sub_Abbr] = 'ENG' THEN [Total_marks] ELSE NULL END) AS [ENG], 
    MAX(CASE WHEN [Sub_Abbr] = 'MBEN' THEN [Total_marks] ELSE NULL END) AS [MBEN], 
    MAX(CASE WHEN [Sub_Abbr] = 'PSc' THEN [Total_marks] ELSE NULL END) AS [PSc], 
    MAX(CASE WHEN [Sub_Abbr] = 'PSY' THEN [Total_marks] ELSE NULL END) AS [PSY] 
FROM 
    [dbo].[prePivot1] 
GROUP BY 
    [StudentId];