mysql建表设置两个默认CURRENT_TIMESTAMP的技巧

转载：http://blog.163.com/user_zhaopeng/blog/static/166022708201252323942430/

 

业务场景:

例如用户表,我们需要建一个字段是创建时间, 一个字段是更新时间.

解决办法可以是指定插入时间,也可以使用数据库的默认时间.

在mysql中如果设置两个默认CURRENT_TIMESTAMP,会出现这样的错误.

ERROR 1293 (HY000): Incorrect table definition; there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE clause.

错误的建表语句:

CREATE TABLE `db1`.`sms_queue` (
  `Id` INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
  `Message` VARCHAR(160) NOT NULL DEFAULT 'Unknown Message Error',
  `CurrentState` VARCHAR(10) NOT NULL DEFAULT 'None',
  `Phone` VARCHAR(14) DEFAULT NULL,
  `Created` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `LastUpdated` TIMESTAMP NOT NULL ON UPDATE CURRENT_TIMESTAMP,
  `TriesLeft` tinyint NOT NULL DEFAULT 3,
  PRIMARY KEY (`Id`)
)
ENGINE = InnoDB;

解决办法,可以使用触发器或者其他,在此还是使用数据库的方式.

建表语句:

create table test_table(
  id integer not null auto_increment primary key,
  stamp_created timestamp default '0000-00-00 00:00:00',
  stamp_updated timestamp default now() on update now()
);

测试:

 mysql> insert into test_table(stamp_created, stamp_updated) values(null, null); 
Query OK, 1 row affected (0.06 sec)

mysql> select * from t5; 
+----+---------------------+---------------------+ 
| id | stamp_created       | stamp_updated       |
+----+---------------------+---------------------+
|  2 | 2009-04-30 09:44:35 | 2009-04-30 09:44:35 |
+----+---------------------+---------------------+
2 rows in set (0.00 sec)  mysql> update test_table set id = 3 where id = 2; Query OK, 1 row affected (0.05 sec) Rows matched: 1  Changed: 1  Warnings: 0  mysql> select * from test_table;+----+---------------------+---------------------+| id | stamp_created       | stamp_updated       | +----+---------------------+---------------------+ |  3 | 2009-04-30 09:44:35 | 2009-04-30 09:46:59 | +----+---------------------+---------------------+ 2 rows in set (0.00 sec) 

解决办法是在stackoverflow看到的,原文网址:

http://stackoverflow.com/questions/267658/having-both-a-created-and-last-updated-timestamp-columns-in-mysql-4-0