SQL Update多表联合修改

1) Oracle 多表更新方法：

Oracle语法: UPDATE updatedtable SET (col_name1[,col_name2…])= (SELECT col_name1,[,col_name2…] FROM srctable [WHERE where_definition])

例子：

	UPDATE 
	A a 
	SET 
	( a.a1, a.a2 ) = ( SELECT b.b1, b, b2 FROM B b WHERE b.b3= a.a3 )

2) MySql多表更新方法：

MySql语法：UPDATE table_references SET col_name1=expr1 [, col_name2=expr2 …] [WHERE where_definition]

例子：

	UPDATE 
	A a,
	B b 
	SET 
		a.a1 = b.b1 ,
		a.a2 = b.b2 
	WHERE
		a.a3 = b.b3

3) SQLServer多表更新方法：

SQLServer语法：
UPDATE { table_name WITH ( < table_hint_limited > [ …n ] ) | view_name | rowset_function_limited } SET { column_name = { expression | DEFAULT | NULL } | @variable = expression | @variable = column = expression } [ ,…n ] { { [ FROM { < table_source > } [ ,…n ] ] [ WHERE < search_condition > ] } | [ WHERE CURRENT OF { { [ GLOBAL ] cursor_name } | cursor_variable_name } ] } [ OPTION ( < query_hint > [ ,…n ] ) ]

例子：

   UPDATE a 
   	SET 
   	a.a1 = b.b1 ,
   	a.a2 = b.b2 
   	FROM
   		A a,
   		B b 
   	WHERE
   		a.a3 = b.b3