MySQL timestamp fields - created/modified

ALTER TABLE 'my_table'
CHANGE `created` TIMESTAMP DEFAULT 0,
CHANGE `modified` TIMESTAMP ON UPDATE CURRENT_TIMESTAMP

But be sure to give any value to created and modified during create and update operations.

Here is an example:

mysql> CREATE TABLE ts_test5 (
-> created TIMESTAMP DEFAULT 0,
-> updated TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
-> data CHAR(30)
-> );
Query OK, 0 rows affected (0.01 sec)

mysql> INSERT INTO ts_test5 (created, data)
-> VALUES (NULL, ‘original_value’);
Query OK, 1 row affected (0.00 sec)

mysql> SELECT * FROM ts_test5;
+---------------------+---------------------+----------------+
| created             |updated              |data            |   
+---------------------+---------------------+----------------+
| 2005-01-04 14:47:39 | 0000-00-00 00:00:00 | original_value |
+---------------------+---------------------+----------------+
1 row in set (0.00 sec)

mysql> . . . time passes . . .

mysql> UPDATE ts_test5 SET data=’updated_value’;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1
Changed: 1
Warnings: 0

mysql> SELECT * FROM ts_test5;
+---------------------+---------------------+---------------+
| created             |updated              |data           |
+---------------------+---------------------+---------------+
| 2005-01-04 14:47:39 | 2005-01-04 14:47:52 | updated_value |
+---------------------+---------------------+---------------+
1 row in set (0.00 sec)

Change

alter table users modify 
   `created` TIMESTAMP NOT NULL DEFAULT '0000-00-00 00:00:00'

To:

alter table users modify 
   `created` TIMESTAMP NOT NULL DEFAULT now()

Or:

alter table users modify 
   `created` TIMESTAMP NOT NULL DEFAULT current_timestamp