Rounding a MYSQL datetime to earliest 15 minute interval in milliseconds (PHP)

Question

I\'m fetching a datetime from MYSQL which looks like:

2010-08-11 11:18:28

I need to convert it into the \"floor\" or the earliest 15 minute interval and outp

Answer 1

The following will give you the earliest 15 minute interval :

select UNIX_TIMESTAMP(YOURDATETIME)-MOD(UNIX_TIMESTAMP(YOURDATETIME), 900) 
from YOURTABLE

The result is in epoch seconds (seconds since '1970-01-01 00:00:00' UTC), if you want that value in milliseconds you should multiply by 1000 (either in the query or in PHP, as you see fit).

EDIT

In PHP for your set of values that would be :

$values = array('2010-08-11 11:18:28', '2010-08-11 11:28:28', '2010-08-11 00:00:00', '2010-08-11 23:59:59');
foreach($values as $value) {
    $result = (strtotime($value)-(strtotime($value) % 900));
    echo "$value -> $result\n";
}

When you multiply $result by 1000 (to get the value in ms) you will probably get an overflow and the result will be converted to a float. This is probably not what you want, so you might be better of using bcmul :

$result = bcmul((strtotime($value)-(strtotime($value) % 900)), 1000);