UNIX_TIMESTAMP(timestamp) use

i am trying to acquire unix_timestamp value for a particular timestam开发者_Go百科p column. but i am confused.

$timecheck = mysql_query("SELECT UNIX_TIMESTAMP(datetime) FROM machine where m_id = $m_id");
                    if (mysql_num_rows($timecheck) > 0){
                        while ($timefetch = mysql_fetch_object($timecheck)) {
                            echo $timefetch->datetime;
                            print_r($timefetch[0]->datetime);
                            if (($timefetch->datetime - time()) > 6000){
                                echo "1";
                            }
                            else {
                                echo "0";
                            }
                            }

the timestamp value returned is an stdClass object. cannot use it to compare. can someone please help me with the below code

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Use an alias for column name in your SQL query:

SELECT UNIX_TIMESTAMP(datetime) AS datetime FROM machine where m_id = $m_id