从日期匹配的选择语句中更新具有多个值的表

Question

我在更新表格时遇到问题，我确定它非常简单，但我在这里转圈圈。

我要更新的表'table1'数据格式如下：

[Month]                    Figure
----------------------------------
2010-05-01 00:00:00.000 1.0000
2010-06-01 00:00:00.000 1.0000
2010-07-01 00:00:00.000 1.0000
2010-08-01 00:00:00.000 1.0000

包含更新数据的表“data1”的格式如下：

[Month]                    Figure
----------------------------------
2010-05-01 00:00:00.000 0.7212
2010-08-01 00:00:00.000 1.2351

我使用的SQL和错误信息如下。

UPDATE t1
SET t1.figure = (SELECT figure from data1)
FROM table1 t1 JOIN data1 d1
ON (t1.[month] = d1.[month])


Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.
The statement has been terminated.

我需要一个while循环来遍历每一行吗？

我希望最终结果如下：

[Month]                    Figure
----------------------------------
2010-05-01 00:00:00.000 0.7212
2010-06-01 00:00:00.000 1.0000
2010-07-01 00:00:00.000 1.0000
2010-08-01 00:00:00.000 1.2351

非常感谢。

Answer 1

您可以为此使用UPDATE FROMsyntax。

看看here和here的语法。

FROM (table_source)

指定表、视图或派生表源用于 提供更新操作的标准

UPDATE  t1
SET     t1.figure = data1.figure
FROM    t1
        INNER JOIN data1 ON data1.month = t1.month

Answer 2

UPDATE t1
SET t1.figure = data1.figure 
FROM table1 t1 JOIN data1 d1
ON (t1.[month] = d1.[month])

Answer 3

SQL Server 2008：

MERGE INTO Table1
USING data1 AS D1
   ON Table1.my_Month = D1.my_Month
WHEN MATCHED 
   THEN UPDATE 
           SET Figure = D1.Figure;

SQL Server 2008 之前的版本：

UPDATE Table1
   SET Figure = (
                 SELECT D1.Figure
                   FROM data1 AS D1
                  WHERE Table1.my_Month = D1.my_Month
                )
 WHERE EXISTS (
               SELECT *
                 FROM data1 AS D1
                WHERE Table1.my_Month = D1.my_Month
              );

请注意，UPDATE..FROM 语法是专有的，当目标行与多个源行匹配时会产生不可预知的结果。