SQL我如何像这样更新?

尝试下面的方法来获得你正在做的事情

UDPATE [MandS].[dbo].[Temp_LTGData] LTGSource 
SET [CORP_REG_NO] = (SELECT [CORP_REG_NO] 
                     FROM [MandS].[dbo].[Temp_LTGData] 
                     WHERE ([CORP_REG_NO] IS NULL 
                          AND [CUSTOMER_NUMBER] = ToUpdate.[CUSTOMER_NUMBER] )) 
FROM {MandS].[dbo].[Temp_LTGData] ToUpdate
where [CORP_REG_NO] IS NULL

类似这样的内容允许您处理具有源行和目标行的许多列

如果需要为不同的列链接不同的行,那么就更复杂了

如果我理解正确,过滤到 CORP_REG_NO IS NULL

Update
   target
Set
   [CORP_REG_NO] = CASE WHEN target.[CORP_REG_NO] IS NULL THEN source.[CORP_REG_NO] ELSE target.[CORP_REG_NO] END,
    ...and again...
FROM
    [MandS].[dbo].[Temp_LTGData] target
    JOIN
    [MandS].[dbo].[Temp_LTGData] source ON target.[CUSTOMER_NUMBER] = source.[CUSTOMER_NUMBER]
WHERE
    a filter to restrict rows perhaps

试试这个:

UPDATE Temp_LTGData LTGSource
  SET Col1 = L2.Col1, Col2 = L2.Col2, Col3 = L2.Col3
FROM LTGSource L1
JOIN LTGSource L2 ON L2.CORP_REG_NO IS NOT NULL AND L1.CUSTOMER_NUMBER = L2.CUSTOMER_NUMBER
WHERE L1.CORP_REG_NO IS NULL