老师,我在MySQL中发现起别名不需要空格也能实现,这是为什么
update emp3 e,(select address from emp3 where emp_id =1)t set e.address =
t.address where e.emp_id = 2;
update emp3 e,(select address from emp3 where emp_id =1) t set e.address =
t.address where e.emp_id = 2;
update emp3 e set e.address = (select t1.address from(select emp_id, addr
ess from emp3) t1 where t1.emp_id=1) where e.emp_id =2;