对于SQL Server 2008 +使用MERGE而不是专有的更新…FROM语法有一些吸引力。

它不仅是标准SQL，因此更易于移植，而且在源端有多个连接行的情况下(因此在更新中可能使用多个不同的值)也会引发错误，而不是最终结果不确定。

MERGE INTO Sales_Import
   USING RetrieveAccountNumber
      ON Sales_Import.LeadID = RetrieveAccountNumber.LeadID
WHEN MATCHED THEN
   UPDATE 
      SET AccountNumber = RetrieveAccountNumber.AccountNumber;

然而，不幸的是，选择使用哪一种可能并不完全取决于首选的风格。SQL Server中MERGE的实现一直受到各种错误的困扰。Aaron Bertrand在这里整理了一份报告的清单。

我想再补充一点。

不要用相同的值更新一个值，这会产生额外的日志记录和不必要的开销。 参见下面的例子-尽管链接了3条记录，但它只会在2条记录上执行更新。

DROP TABLE #TMP1
DROP TABLE #TMP2
CREATE TABLE #TMP1(LeadID Int,AccountNumber NVarchar(50))
CREATE TABLE #TMP2(LeadID Int,AccountNumber NVarchar(50))

INSERT INTO #TMP1 VALUES
(147,'5807811235')
,(150,'5807811326')
,(185,'7006100100007267039');

INSERT INTO #TMP2 VALUES
(147,'7006100100007266957')
,(150,'7006100100007267039')
,(185,'7006100100007267039');

UPDATE A
SET A.AccountNumber = B.AccountNumber
FROM
    #TMP1 A 
        INNER JOIN #TMP2 B
        ON
        A.LeadID = B.LeadID
WHERE
    A.AccountNumber <> B.AccountNumber  --DON'T OVERWRITE A VALUE WITH THE SAME VALUE

SELECT * FROM #TMP1

Oracle 11 g

merge into Sales_Import
using RetrieveAccountNumber
on (Sales_Import.LeadId = RetrieveAccountNumber.LeadId)
when matched then update set Sales_Import.AccountNumber = RetrieveAccountNumber.AccountNumber;

MS Sql

UPDATE  c4 SET Price=cp.Price*p.FactorRate FROM TableNamea_A c4
inner join TableNamea_B p on c4.Calcid=p.calcid 
inner join TableNamea_A cp on c4.Calcid=cp.calcid 
WHERE c4..Name='MyName';

Oracle 11 g

        MERGE INTO  TableNamea_A u 
        using
        (
                SELECT c4.TableName_A_ID,(cp.Price*p.FactorRate) as CalcTot 
                FROM TableNamea_A c4
                inner join TableNamea_B p on c4.Calcid=p.calcid 
                inner join TableNamea_A cp on c4.Calcid=cp.calcid 
                WHERE p.Name='MyName' 
        )  rt
        on (u.TableNamea_A_ID=rt.TableNamea_B_ID)
        WHEN MATCHED THEN
        Update set Price=CalcTot  ;

这将允许您根据未在另一个表中找到的列值更新表。

UPDATE table1 SET table1.column = 'some_new_val' WHERE table1.id IN (
        SELECT * 
        FROM (
                SELECT table1.id
                FROM  table1 
                LEFT JOIN table2 ON ( table2.column = table1.column ) 
                WHERE table1.column = 'some_expected_val'
                AND table12.column IS NULL
        ) AS Xalias
)

这将根据在两个表中找到的列值更新一个表。

UPDATE table1 SET table1.column = 'some_new_val' WHERE table1.id IN (
        SELECT * 
        FROM (
                SELECT table1.id
                FROM  table1 
                JOIN table2 ON ( table2.column = table1.column ) 
                WHERE table1.column = 'some_expected_val'
        ) AS Xalias
)

如果以上答案不适合你，试试这个

Update Sales_Import A left join RetrieveAccountNumber B on A.LeadID = B.LeadID
Set A.AccountNumber = B.AccountNumber
where A.LeadID = B.LeadID