现有两个测试表，user和student，数据如下

mysql> select * from user;+----+------+--------+-----+---------------------+| id | name | gender | age | updated_time        |+----+------+--------+-----+---------------------+|  1 | 张三     | M      |  18 | 2018-11-05 10:50:40 ||  2 | 李四     | M      |  17 | 2018-11-05 10:51:28 ||  3 | 王五     | W      |  18 | 2018-11-05 10:51:44 |+----+------+--------+-----+---------------------+3 rows in set (0.00 sec)mysql> select * from student;+----+------+------+------+-----------+---------------------+| id | name | sex  | age  | school    | updated_time        |+----+------+------+------+-----------+---------------------+|  1 | 张三     | NULL | NULL | 高二(1)班      | 2018-11-05 10:55:12 ||  2 | 李四     | NULL | NULL | 高二(3)班      | 2018-11-05 10:55:28 ||  3 | 王五     | NULL | NULL | 高二(1)班      | 2018-11-05 10:55:39 |+----+------+------+------+-----------+---------------------+3 rows in set (0.00 sec)

将user中的age和gender更新到student中的age和sex上

mysql> update student s,user u set s.sex=u.gender,s.age=u.age where s.name=u.name;Query OK, 3 rows affected (0.03 sec)Rows matched: 3  Changed: 3  Warnings: 0mysql> select * from student;+----+------+------+------+-----------+---------------------+| id | name | sex  | age  | school    | updated_time        |+----+------+------+------+-----------+---------------------+|  1 | 张三     | M    |   18 | 高二(1)班      | 2018-11-05 11:21:23 ||  2 | 李四     | M    |   17 | 高二(3)班      | 2018-11-05 11:21:23 ||  3 | 王五     | W    |   18 | 高二(1)班      | 2018-11-05 11:21:23 |+----+------+------+------+-----------+---------------------+3 rows in set (0.00 sec)

现在PostgreSQL中有是相同的表，相同的数据，相同的需求，更新语句如下

update student set age=u.age,sex=u.gender from "user" u where student.id=u.id;