我想在一个表中更新一个列，在其他表上进行连接，例如:
UPDATE table1 a
INNER JOIN table2 b ON a.commonfield = b.[common field]
SET a.CalculatedColumn= b.[Calculated Column]
WHERE
b.[common field]= a.commonfield
AND a.BatchNO = '110'
但它在抱怨:
警报170,15层，状态1,2号线 第2行:'a'附近的语法错误。
这里出了什么问题?
当前回答
你还没有完全掌握SQL Server专有的UPDATE FROM语法。也不知道为什么你需要在CommonField上加入，然后还对它进行过滤。试试这个:
UPDATE t1
SET t1.CalculatedColumn = t2.[Calculated Column]
FROM dbo.Table1 AS t1
INNER JOIN dbo.Table2 AS t2
ON t1.CommonField = t2.[Common Field]
WHERE t1.BatchNo = '110';
如果你在做一些愚蠢的事情——比如不断地试图将一列的值设置为另一列的总和(这违反了避免存储冗余数据的原则)，你可以使用CTE(公共表表达式)——请参阅这里和这里了解更多细节:
;WITH t2 AS
(
SELECT [key], CalculatedColumn = SUM(some_column)
FROM dbo.table2
GROUP BY [key]
)
UPDATE t1
SET t1.CalculatedColumn = t2.CalculatedColumn
FROM dbo.table1 AS t1
INNER JOIN t2
ON t1.[key] = t2.[key];
之所以这么做很愚蠢，是因为每次table2中的任何一行发生变化时，都必须重新运行整个更新。SUM是可以在运行时计算的东西，这样就不必担心结果是陈旧的。
其他回答
Try:
UPDATE table1
SET CalculatedColumn = ( SELECT [Calculated Column]
FROM table2
WHERE table1.commonfield = [common field])
WHERE BatchNO = '110'
我想，这就是你要找的。
UPDATE
Table1
SET
Table1.columeName =T1.columeName * T2.columeName
FROM
Table1 T1
INNER JOIN Table2 T2
ON T1.columeName = T2.columeName;
UPDATE mytable
SET myfield = CASE other_field
WHEN 1 THEN 'value'
WHEN 2 THEN 'value'
WHEN 3 THEN 'value'
END
From mytable
Join otherTable on otherTable.id = mytable.id
Where othertable.somecolumn = '1234'
这里有更多的选择。
MERGE table1 T
USING table2 S
ON T.CommonField = S."Common Field"
AND T.BatchNo = '110'
WHEN MATCHED THEN
UPDATE
SET CalculatedColumn = S."Calculated Column";
另一种方法是使用MERGE
;WITH cteTable1(CalculatedColumn, CommonField)
AS
(
select CalculatedColumn, CommonField from Table1 Where BatchNo = '110'
)
MERGE cteTable1 AS target
USING (select "Calculated Column", "Common Field" FROM dbo.Table2) AS source ("Calculated Column", "Common Field")
ON (target.CommonField = source."Common Field")
WHEN MATCHED THEN
UPDATE SET target.CalculatedColumn = source."Calculated Column";
-Merge是SQL标准的一部分
-我也很确定内部连接更新是不确定的。 类似的问题，答案是这样说的 http://ask.sqlservercentral.com/questions/19089/updating-two-tables-using-single-query.html
