Update 两张表之间的数据

1.

update t1 
        set t1.c2 = t2.c2
      from t2

where t1.c1 = t2.c1

2.

Update t1 
        set t1.c2 = t2.c2

from t1 inner join t2 
        on t1.c1 = t2.c1