我正在尝试在 MySQL 表中保存时间。但是，日期恢复为 2000-01-01。
1.9.2p320 :036 > vv = Visitor.new
=> #<Visitor id: nil, ip_address: nil, num_day_visits: nil, last_visit: nil>
1.9.2p320 :037 > vv.last_visit = Time.now; vv.ip_address = "3.3.3.3"
=> "3.3.3.3"
1.9.2p320 :038 > vv.num_day_visits = 1
=> 1
1.9.2p320 :039 > vv
=> #<Visitor id: nil, ip_address: "3.3.3.3", num_day_visits: 1, last_visit: "2012-10-11 01:31:04">
1.9.2p320 :040 > vv.save
SQL (0.2ms) BEGIN
SQL (0.7ms) INSERT INTO `visitors` (`ip_address`, `last_visit`, `num_day_visits`) VALUES (?, ?, ?) [["ip_address", "3.3.3.3"], ["last_visit", 2012-10-11 01:31:04 -0400], ["num_day_visits", 1]]
(0.5ms) COMMIT
=> true
1.9.2p320 :042 > vv
=> #<Visitor id: 1199, ip_address: "3.3.3.3", num_day_visits: 1, last_visit: "2012-10-11 01:31:04">
1.9.2p320 :043 > Visitor.find(:all,:conditions=>{:ip_address => "3.3.3.3"})
Visitor Load (1.4ms) SELECT `visitors`.* FROM `visitors` WHERE `visitors`.`ip_address` = '3.3.3.3'
=> [#<Visitor id: 1199, ip_address: "3.3.3.3", num_day_visits: 1, last_visit: "2000-01-01 05:31:04">]
所以当我检索记录时，日期是 2000-01-01。
MySQL中的表:
mysql> describe visitors ;
+----------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| ip_address | varchar(255) | NO | | NULL | |
| num_day_visits | int(11) | NO | | NULL | |
| last_visit | time | NO | | NULL | |
+----------------+--------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
更新:我创建了一个玩具表来玩弄从时间到日期时间的转换。这是发生了什么:
mysql> select * from example ;
+----+----------+
| id | mytime |
+----+----------+
| 1 | 11:13:00 |
+----+----------+
1 row in set (0.00 sec)
mysql> alter table example change mytime mytime datetime;
Query OK, 1 row affected, 1 warning (0.02 sec)
Records: 1 Duplicates: 0 Warnings: 1
mysql> select * from example ;
+----+---------------------+
| id | mytime |
+----+---------------------+
| 1 | 0000-00-00 00:00:00 |
+----+---------------------+
1 row in set (0.00 sec)
这样就破坏了值(value)。我试图通过将表更改为时间并使用新行来返回。重新开始:
mysql> select * from example ;
+----+----------+
| id | mytime |
+----+----------+
| 2 | 11:13:00 |
+----+----------+
1 row in set (0.00 sec)
mysql> ALTER TABLE example CHANGE mytime mytime DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP();
ERROR 1067 (42000): Invalid default value for 'mytime'
mysql> ALTER TABLE example CHANGE mytime mytime DATETIME NOT NULL DEFAULT CURRENT_DATE();
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'CURRENT_DATE()' at line 1
显然，this is hard .
最佳答案
这是因为您的 last_visit 列是 time 而不是 datetime 类型。最初我假设 mysql 只是使用 01-01-2000 作为内部表示时间字段的某种默认日期，但看起来 01-01-2000 是 rails 而不是 mysql 所做的。看Represent a time with no date in ruby
关于mysql - 日期从 ActiveRecord 恢复到 2000-01-01 到 MySQL，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12832857/