方法一：
update table1 set field1=table2.field1 from table2
where
table1.id=table2.id
--简写
update
t1
set
t1.c2 = t2.c2
from
t2
where
t1.c1 = t2.c1
方法二：
update
table1
set
field1=(
select
top
1 field1
from
table2
where
table2.id=table1.id)
where
table1.id
in
(condition)