SQLSERVER将一张表的数据更新到另外一张表

UPDATE DC_AQMS_SITE

SET DC_AQMS_SITE.POINTNAME= AQMS_AIR_SITE.POINTNAME

from DC_AQMS_SITE ,AQMS_AIR_SITE

WHERE

DC_AQMS_SITE.MN= AQMS_AIR_SITE.MNCODE

AND DC_AQMS_SITE.POINTNAME<> AQMS_AIR_SITE.POINTNAME

UPDATE DC_AQMS_SITE

SET POINTNAME= A.POINTNAME

from DC_AQMS_SITE D ,AQMS_AIR_SITE  A

WHERE

D.MN= A.MNCODE

AND D.POINTNAME<> A.POINTNAME