Question

在下表中，＆＃34; ColumnDifference＆＃34;：

＆＃34; ColumnName＆＃34;中的每个单元格是另一个表中列的名称，＆＃34; regressionDifferences＆＃34;。我必须从regressionDifferences中选择ColumnName中列出的每个列，在UniqueID上匹配，并将每个字符串中的前八个字符插入ColumnContent。

到目前为止，我有：

DECLARE @LoopCounter INT = 1, @MaxRowNumber INT = 420,
@ColumnName VARCHAR(max), @UniqueID VARCHAR(max), @ColumnContent VARCHAR(max), @SQL VARCHAR(max), @table VARCHAR(max)

WHILE(@LoopCounter < @MaxRowNumber)
BEGIN
SELECT @ColumnName = ColumnName
FROM ColumnDifference WHERE RowNumber = @LoopCounter

SELECT @ColumnContent = ColumnContent
FROM ColumnDifference WHERE RowNumber = @LoopCounter

SELECT @UniqueID = UniqueID
FROM ColumnDifference WHERE RowNumber = @LoopCounter

SET @sql = 'UPDATE ColumnDifference
SET ' + @ColumnContent + ' = (SELECT DISTINCT SUBSTRING(' + @ColumnName + ',0,9) FROM regressionDifferences rD 
WHERE rD.UniqueID LIKE '''
                  + @UniqueID + '%'')'

exec(@sql);

SET @LoopCounter = @LoopCounter + 1

END

如果我将@sql设置为：

'SELECT DISTINCT SUBSTRING(' + @ColumnName + ',0,9) FROM regressionDifferences rD WHERE rD.UniqueID LIKE ''' + @UniqueID + '%'''

我得到了正确的结果，但都在不同的表中：

Screenshot of SELECT

如果我打印原始的@sql，我会得到一个空白的消息框。

执行时，我得到＆＃34;命令已成功完成＆＃34;但在ColumnDifference中没有任何变化。任何帮助将不胜感激！

由于

Answer 1

如果这可以为您提供所需的结果，则可以编写更新：

DECLARE @LoopCounter INT = 1 , @total as  int , @colname as varchar(10) , @sql as nvarchar(1000)

--- getting the max no of rows
set @total =(select count(*) from 
(select cd.ColumnName, row_number ()over(order by rd.UniqueID) as rw  from regressionDifferences rd
inner join ColumnDifference cd on rd.UniqueID = cd.UniqueID)t)


WHILE(@LoopCounter < @total)
BEGIN

--- select one row at a time
set @colname = (select t.ColumnName from (select cd.ColumnName, row_number ()over(order by rd.UniqueID) as rw  from regressionDifferences rd
inner join ColumnDifference cd on rd.UniqueID = cd.UniqueID)t
where t.rw=@LoopCounter)


SET @sql = 'SELECT SUBSTRING(' + @colname + ',0,9) FROM regressionDifferences rD'

exec(@sql);

SET @LoopCounter = @LoopCounter + 1

END

Answer 2

.normaltag { color: red; }出现问题。看看它应该如何。这应该有效：

SET ' + @ColumnContent'

我还修复了初始选择：您根本不需要提取DECLARE @LoopCounter INT = 1, @MaxRowNumber INT = 420, @ColumnName VARCHAR(max), @UniqueID VARCHAR(max), @SQL VARCHAR(max), @table VARCHAR(max); WHILE(@LoopCounter < @MaxRowNumber) BEGIN SELECT @ColumnName = ColumnName , @UniqueID = UniqueID FROM ColumnDifference WHERE RowNumber = @LoopCounter; SET @sql = 'UPDATE ColumnDifference SET ColumnContent = (SELECT DISTINCT SUBSTRING(' + @ColumnName + ',0,9) FROM regressionDifferences rD WHERE rD.UniqueID = ''' + @UniqueID + ''')'; PRINT @sql; exec(@sql); SET @LoopCounter += 1; END（或者是吗？）。
我带走了@ColumnContent：有LIKE，它必须是唯一的，不喜欢。
其他一些小变化。

使用动态SQL更新表

2 个答案: