求高手解决数据批量修改语句,该如何解决

求高手解决数据批量修改语句
mssql数据库中有两个表A、B；表A中有列X、Y,表B中有列M、N，X、Y,M、N中都有数据,如何用数据表A中X列数据,整体替换数据表B中M列数据.
求高手帮助解决.

[解决办法]

SQL code

update bsetm = xfroma join b on a.x = b.x and a.y = b.y
[解决办法]
SQL code
use DBTestgoif OBJECT_ID('A') is not null drop table Agocreate table A(X int,Y int)goinsert into Aselect 1,1 union allselect 2,2create table B(X int,Y int,M int,N int)goinsert into Bselect 1,1,11,11 union allselect 2,2,22,22UPDATE BSET M=A.XFROM A INNER JOIN BON A.X=B.X AND A.Y=B.Y
[解决办法]
SQL code
UPDATE B SET M=(SELECT X FROM A ta WHERE ta.X=tb.X AND ta.Y=tb.Y) FROM B tb