UNIX Timestamp to MySQL DATETIME

Question

I have a table with statistics and a field named time with Unix Timestamps.

There are about 200 rows in the table, but I would like to change the Unix timestamps to MySQL DATETIME without losing the current rows. The current table:

CREATE TABLE `stats` (
    `id` int(11) unsigned NOT NULL auto_increment,
    `time` int(11) NOT NULL,
    `domain` varchar(40) NOT NULL,
    `ip` varchar(20) NOT NULL,
    `user_agent` varchar(255) NOT NULL,
    `domain_id` int(11) NOT NULL,
    PRIMARY KEY  (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8

So the time (INT) should be a DATETIME field.

How can I update the Unix Timestamp to MySQL's DATETIME?

Solution 1

Remember to test it before using it for real, this is written from memory but should give you a good idea.

ALTER TABLE `stats` CHANGE `time` `unix_time` int(11) NOT NULL // rename the old column
ALTER TABLE `stats` ADD `time` DATETIME NOT NULL // create the datetime column
UPDATE `stats` SET `time`=FROM_UNIXTIME(unix_time) // convert the data
ALTER TABLE `stats` DROP `unix_time` // drop the old unix time column

Solution 2

1. use alter table to create a new column (eg. time2) with the datetime type in the same table
2. update stats set time2=from_unixtime(time);
3. use alter table to a) delete the time column, and b) rename the time2 to time.