Oracle关联表进行修改操作(查询某个表，以某个表作为基础，修改其它表)

merge into tableA a
using(
  
 SELECT  a,b,c from tableB
) b 
on (a.id = b.id)//这里一定要用括号包起来....
 when matched then
update set 
a.a=b.a, 
a.b= b.b, 
a.c= b.c