m表：
| id | m_name |
| 11 | tom |
| 22 | jack |
c表:
| id | mid | c_name | m_name |
| 1 | 11 | tom child 1 | |
| 2 | 22 | jack child 1 | |
| 3 | 22 | jack child 2 |
UPDATE c SET m_name=(SELECT m_name FROM m WHERE c.mid = m.id) oracle里面可以更新多个字段：
update TC_ECH_FILE set (tc_ech36,tc_ech37,tc_ech38,tc_ech39,tc_ech40,tc_ech41,tc_ech34,tc_ech35) =
(
SELECT tc_ece29,tc_ece30,tc_ece31,tc_ece32,tc_ece33, tc_ece28, tc_ece34,tc_ece35
from TC_ECE_FILE where TC_ECE_FILE.tc_ece01 = TC_ECH_FILE.tc_ech33 AND TC_ECE_FILE.tc_ece02 = TC_ECH_FILE.tc_ech05
)