MYSQL自动写入当前时间。

定义t5由一个自增字段，一个默认当前时间戳并update时随动更新字段组成。

mysql> CREATE TABLE t5 (

id int NOT NULL AUTO_INCREMENT PRIMARY KEY,

css timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,

v int(11) DEFAULT NULL );

Query OK, 0 rows affected (0.13 sec)

mysql> insert into t5(v) values (1);

Query OK, 1 row affected (0.06 sec)

mysql> select * from t5;

+----+---------------------+------+

| id | css | v |

+----+---------------------+------+

| 1 | 2012-09-06 08:04:29 | 1 |

+----+---------------------+------+

1 row in set (0.00 sec)

mysql> update t5 set v=2;

Query OK, 1 row affected (0.03 sec)

Rows matched: 1 Changed: 1 Warnings: 0

mysql> select * from t5;

+----+---------------------+------+

| id | css | v |

+----+---------------------+------+

| 1 | 2012-09-06 08:04:44 | 2 |

+----+---------------------+------+

1 row in set (0.00 sec)

mysql> insert into t6 values(); --这样的情况有意思