mysql时间问题_MySQL

mysql> desc test_time;+--------+---------------------+------+-----+-------------------+-----------------------------+| Field | Type | Null | Key | Default | Extra |+--------+---------------------+------+-----+-------------------+-----------------------------+| id | bigint(20) unsigned | NO | PRI | NULL | auto_increment || t_date | date | YES | | NULL | || t_time | time | YES | | NULL | || t_ts | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP || t_dt | datetime | YES | | NULL | |+--------+---------------------+------+-----+-------------------+-----------------------------+5 rows in set (0.00 sec)mysql> insert into test_time(t_date,t_time,t_dt) values(curdate(),curtime(), now());Query OK, 1 row affected (0.00 sec)mysql> select * from test_time;+----+------------+----------+---------------------+---------------------+| id | t_date | t_time | t_ts | t_dt |+----+------------+----------+---------------------+---------------------+| 1 | 2014-06-19 | 15:53:39 | 2014-06-19 15:53:39 | 2014-06-19 15:53:39 || 2 | 2014-06-19 | 15:53:57 | 2014-06-19 15:53:57 | 2014-06-19 15:53:57 || 3 | 2014-06-19 | 15:54:01 | 2014-06-19 15:54:01 | 2014-06-19 15:54:01 || 4 | 2014-06-19 | 15:54:38 | 2014-06-19 15:54:38 | 2014-06-19 15:54:38 |+----+------------+----------+---------------------+---------------------+4 rows in set (0.00 sec)

mysql> update test_time set age=4 where id=4;Query OK, 1 row affected (0.00 sec)Rows matched: 1 Changed: 1 Warnings: 0mysql> mysql> select * from test_time;+----+------------+----------+---------------------+---------------------+-----+| id | t_date | t_time | t_ts | t_dt | age |+----+------------+----------+---------------------+---------------------+-----+| 1 | 2014-06-19 | 15:53:39 | 2014-06-19 15:59:32 | 2014-06-19 15:53:39 | 1 || 2 | 2014-06-19 | 15:53:57 | 2014-06-19 15:59:41 | 2014-06-19 15:53:57 | 2 || 3 | 2014-06-19 | 15:54:01 | 2014-06-19 15:59:49 | 2014-06-19 15:54:01 | 3 || 4 | 2014-06-19 | 15:54:38 | 2014-06-19 15:59:55 | 2014-06-19 15:54:38 | 4 |+----+------------+----------+---------------------+---------------------+-----+

mysql> SELECT * FROM test_time WHERE TO_DAYS(NOW()) - TO_DAYS(t_date) <= 30;+----+------------+----------+---------------------+---------------------+-----+| id | t_date | t_time | t_ts | t_dt | age |+----+------------+----------+---------------------+---------------------+-----+| 1 | 2014-06-19 | 15:53:39 | 2014-06-19 15:59:32 | 2014-06-19 15:53:39 | 1 || 2 | 2014-06-19 | 15:53:57 | 2014-06-19 15:59:41 | 2014-06-19 15:53:57 | 2 || 3 | 2014-06-19 | 15:54:01 | 2014-06-19 15:59:49 | 2014-06-19 15:54:01 | 3 || 4 | 2014-06-19 | 15:54:38 | 2014-06-19 15:59:55 | 2014-06-19 15:54:38 | 4 |+----+------------+----------+---------------------+---------------------+-----+4 rows in set (0.00 sec)

select * from test_time where unix_timestamp(t_ts) >= unix_timestamp() -1800 and unix_timestamp(t_ts) <= unix_timestamp();