MySQL与SQLServer的update left join语法区别

需求： 

表A 字段 A_ID, A_NAME, B_ID 
表B 字段 B_ID, B_NAME 

需求把A的所有A_NAME更新为相应的B的 B_NAME。 

mysql做法： 

UPDATE A  
LEFT JOIN  
 B  
ON   
 A.B_ID = B.B_ID  
SET   
 A.A_NAME = B.B_NAME;  

MSSQL做法： 

update A  
set A_NAME = B.B_NAME  
from A left join B   
ON   
 A.B_ID = B.B_ID