mysql> desc test200;
+---------------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------+----------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| registerTime | datetime | YES | | NULL | |
| lastLoginTime | datetime | YES | | NULL | |
+---------------+----------+------+-----+---------+-------+
3 rows in set (0.00 sec) mysql> select * from test200;
+------+---------------------+---------------------+
| id | registerTime | lastLoginTime |
+------+---------------------+---------------------+
| 1 | 2016-10-21 09:06:23 | 2016-10-21 09:06:56 |
| 1 | 2016-10-21 09:16:11 | 2016-10-21 09:16:11 |
+------+---------------------+---------------------+
2 rows in set (0.00 sec) mysql> select lastLoginTime - registerTime from test200;
+------------------------------+
| lastLoginTime - registerTime |
+------------------------------+
| 33 |
| 0 |
+------------------------------+
2 rows in set (0.00 sec) mysql> select (UNIX_TIMESTAMP(lastLoginTime) - UNIX_TIMESTAMP(registerTime)) from test200;
+----------------------------------------------------------------+
| (UNIX_TIMESTAMP(lastLoginTime) - UNIX_TIMESTAMP(registerTime)) |
+----------------------------------------------------------------+
| 33 |
| 0 |
+----------------------------------------------------------------+
2 rows in set (0.00 sec) mysql> select now(),lastLoginTime,(UNIX_TIMESTAMP(now()) - UNIX_TIMESTAMP(lastLoginTime)) from test200;
+---------------------+---------------------+---------------------------------------------------------+
| now() | lastLoginTime | (UNIX_TIMESTAMP(now()) - UNIX_TIMESTAMP(lastLoginTime)) |
+---------------------+---------------------+---------------------------------------------------------+
| 2016-10-21 09:32:32 | 2016-10-21 09:06:56 | 1536 |
| 2016-10-21 09:32:32 | 2016-10-21 09:16:11 | 981 |
+---------------------+---------------------+---------------------------------------------------------+
2 rows in set (0.01 sec)