在SQL Server中使用JOIN更新表？

Question

我想更新表中的列,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'

但它抱怨:

消息170,级别15,状态1,行2
第2行:'a'附近的语法不正确.

这有什么不对？

Answer 1

您没有完全使用SQL Server的专有UPDATE FROM语法.也不确定为什么你需要加入CommonField并在之后过滤它.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';

如果您正在做一些非常愚蠢的事情 - 比如不断尝试将一列的值设置为另一列的聚合(这违反了避免存储冗余数据的原则),您可以使用CTE(公用表表达式) - 请参阅此处和这里的更多详细信息:

;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];

这真的很愚蠢的原因是,每次table2更改任何行时,您都必须重新运行整个更新.A SUM是您可以随时在运行时计算的东西,在这样做时,永远不必担心结果是陈旧的.

Answer 2

试试这样:

begin tran
    UPDATE a 
    SET a.CalculatedColumn= b.[Calculated Column]
    FROM table1 a INNER JOIN table2 b ON a.commonfield = b.[common field] 
    WHERE a.BatchNO = '110'
commit tran

Answer 3

Aaron上面给出的答案是完美的:

UPDATE a
  SET a.CalculatedColumn = b.[Calculated Column]
  FROM Table1 AS a
  INNER JOIN Table2 AS b
  ON a.CommonField = b.[Common Field]
  WHERE a.BatchNo = '110';

只是想在我们尝试在更新该表时使用表的别名时添加为什么在SQL Server中出现此问题,下面提到的语法总是会给出错误:

update tableName t 
set t.name = 'books new' 
where t.id = 1

如果要更新单个表或使用join进行更新,则case可以是any.

虽然上面的查询在PL/SQL中可以正常工作,但在SQL Server中却不行.

在SQL Server中使用表别名时更新表的正确方法是:

update t 
set t.name = 'books new' 
from tableName t 
where t.id = 1

希望它能帮助每个人为什么错误来到这里.

Answer 4

    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'

更多选择在这里。

Answer 5

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";