Having both a Created and Last Updated timestamp columns in MySQL 4.0

Question

I have the following table schema;

CREATE TABLE `db1`.`sms_queue` (
  `Id` INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
  `Message` VARCHAR(160) NOT NULL DEFAUL         


        

Answer 1

There is a trick to have both timestamps, but with a little limitation.

You can use only one of the definitions in one table. Create both timestamp columns like so:

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() 
); 

Note that it is necessary to enter null into both columns during insert:

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

mysql> select * from test_table; 
+----+---------------------+---------------------+ 
| 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)