本人初学SQL，求高手个语句 - MS-SQL Server / 基础类

假如有两张表A、B
A中有两列数据，列名分别是BH1、201005（列201005为空）
B中有两列数据，列名分别是BH2、ggg（列ggg中有值）
A中BH1等于B中BH2时，要使A中201005取B中ggg的值，如何实现？

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SQL code:
update a set a.[201005]=b.ggg from b where a.bh1=b.bh2

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update A set [201005]=ggg from B WHERE BH1=BH2

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SQL code:
update
a
set
[201005]=n.ggg
from
a,b
where
a.bh1=b.bh2

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select A.BH1,B.ggg from A,B where A.BH1=B.BH2

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up!

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引用

引用 1 楼 htl258 的回复:
SQL code
update a set a.[201005]=b.ggg from b where a.bh1=b.bh2


update
a
set
[201005]=b.ggg
from
a,b
where
a.bh1=b.bh2

不能用a.[201005]

为什么

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SQL code:
--> 生成测试数据表: [a]
IF OBJECT_ID('[a]') IS NOT NULL
DROP TABLE [a]
GO
CREATE TABLE [a] ([BH1] [nvarchar](10),[201005] [nvarchar](10))
INSERT INTO [a]
SELECT '001',NULL UNION ALL
SELECT '002',NULL

--> 生成测试数据表: [b]
IF OBJECT_ID('[b]') IS NOT NULL
DROP TABLE [b]
GO
CREATE TABLE [b] ([BH