When I was yound and stupid had little experiance, I decided it would be a good idea, to generate timestamps in PHP and store them in INT column in my MySQL innodb table. Now, when this table has millions of records and needs some date-based queries, it is time to convert this column to TIMESTAMP. How do I do this?
Currenlty, my table looks like this:
id (INT) | message (TEXT) | date_sent (INT)
———————————————
1 | hello? | 1328287526
2 | how are you? | 1328287456
3 | shut up | 1328234234
4 | ok | 1328678978
5 | are you… | 1328345324
Here are the queries I came up with, to convert date_sent column to TIMESTAMP:
— creating new column of TIMESTAMP type
ALTER TABLE `pm`
ADD COLUMN `date_sent2` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP();
— assigning value from old INT column to it, in hope that it will be recognized as timestamp
UPDATE `pm` SET `date_sent2` = `date_sent`;
— dropping the old INT column
ALTER TABLE `pm` DROP COLUMN `date_sent`;
— changing the name of the column
ALTER TABLE `pm` CHANGE `date_sent2` `date_sent` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP();
Everything seems correct to me, but when time comes for the UPDATEpmSETdate_sent2=date_sent;, I get a warning and timestamp value remains empty:
+———+——+————————————————–+
| Level | Code | Message |
+———+——+————————————————–+
| Warning | 1265 | Data truncated for column ‘date_sent2’ at row 1 |
What am I doing wrong and is there a way to fix this?
解决方案
You’re nearly there, use FROM_UNIXTIME() instead of directly copying the value.
— creating new column of TIMESTAMP type
ALTER TABLE `pm`
ADD COLUMN `date_sent2` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP();
— Use FROM_UNIXTIME() to convert from the INT timestamp to a proper datetime type
— assigning value from old INT column to it, in hope that it will be recognized as timestamp
UPDATE `pm` SET `date_sent2` = FROM_UNIXTIME(`date_sent`);
— dropping the old INT column
ALTER TABLE `pm` DROP COLUMN `date_sent`;
— changing the name of the column
ALTER TABLE `pm` CHANGE `date_sent2` `date_sent` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP();