MySQL two column timestamp default NOW value problem

Question

I have table as shown below. In order to workaround one default now column restriction of MySQL I used the tip as shown here

CREATE  TABLE IF NOT EXISTS mytable (
  id INT NOT NULL AUTO_INCREMENT ,
  create_date TIMESTAMP NULL DEFAULT '0000-00-00 00:00:00' ,
  update_date TIMESTAMP NULL DEFAULT NOW() ON UPDATE NOW() ,
  PRIMARY KEY (`parti_id`) )
ENGINE = InnoDB;

My sql_mode does not include NO_ZERO_DATE as pointed here my output :

mysql> SELECT @@sql_mode;
+------------+
| @@sql_mode |
+------------+
|            | 
+------------+
1 row in set (0.00 sec)

It is still giving the error as shown below:

ERROR 1067 (42000) at line xx in file: '/myschema.sql': Invalid default value for 'create_date'

I use MySQL 5.1.37 on Ubuntu

How can I fix it? Thanks.

Answer 1

You can only have ONE timestamp column that defaults to CURRENT_TIMESTAMP or NOW() per table. This is a well known bug in MySQL.

To overcome this, make your default for the created column a valid timestamp value, then insert the timestamp in your CRUD application code. Use NOW() or CURRENT_TIMESTAMP for your updated column default.

Reference material: http://dev.mysql.com/doc/refman/5.1/en/timestamp.html

To further illustrate MySQL's shortcoming in this area, consider the following code:

CREATE TABLE testing_timestamps (
id INT NOT NULL AUTO_INCREMENT,
pk_id INT NOT NULL,
col1 TIMESTAMP DEFAULT 0,
col2 TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY(id)
);
--
delimiter $$
CREATE TRIGGER testing_timestamps_trigger
AFTER INSERT ON testing_timestamps
FOR EACH ROW 
BEGIN
UPDATE testing_timestamps SET col1 = NOW() WHERE id = MAX(id);
END;
$$
delimiter ;
--
INSERT INTO testing_timestamps (id) VALUES (0);

The output from this will display: mysql> INSERT INTO testing_timestamps (id) VALUES (0); ERROR 1442 (HY000): Can't update table 'testing_timestamps' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.

This is a bummer because using a trigger in this instance would be a good work around.