Correct Date and Time Columns in MySQL - php

Question

I have a timezone mismatch I need to correct in a table. All dates and times before unix timestamp 1253568477 need to have 5 hours added to their values to make them equal GMT.
I have the following columns...
date (data type date), off by -5 hours
time (data type time), off by -5 hours
timestamp (data type int), this column is the correct time
The reason the timezones are off is because of the way I was setting the values when inserting the rows...
$sql = "insert into email_opens (userid, email, serial, date, time, timestamp) values (
'$userid',
'$opened_by',
'$serial_number',
now(),
now()',
'".gmmktime()."'
)";
The now() value was using the server timezone (eastern) whereas the gmmktime value specified GMT. I have since corrected this query to always use GMT.
Is there a way I can add 5 hours to both time and date columns for those rows where timestamp < 1253568477 in one batch query?
Clarification:
My goal is to update each incorrect row in the table with the correct time by adding 5 hours to each value.

Answer 1

Try with this:
UPDATE mail_opens SET date = DATE_ADD(CONCAT(date, ' ', time), INTERVAL 5 HOUR), time = DATE_ADD(CONCAT(date, ' ', time), INTERVAL 5 HOUR);
And then you probably need this:
<?php
echo date('Y-m-d H:i:s')."<br>";
$addhours = strtotime('+5 hour');
echo $addhours."<br>";
$newdate = date('Y-m-d H:i:s', $addhours);
echo $newdate;
?>
So, using that:
<?php
$addhours = strtotime('+5 hour');
$newdate = date('Y-m-d H:i:s', $addhours);
$sql = "insert into email_opens (userid, email, serial, date, time, timestamp) values (
'$userid',
'$opened_by',
'$serial_number',
'$newdate',
'$newdate',
'".gmmktime()."'
)";
?>

Answer 2

sure, work out the time you corrected the problem so you know only to update records that have a value less than the unix timestamp of your timezone change.
Then update the field and add 60 * 60 * 5 (5 hours in seconds) to those records.
So, your query would be the following:
UPDATE email_opens SET timestamp = (timestamp + 18000) WHERE timestamp < 1253568477;
Cool.