$gdate = date("Y-m-d", strtotime('today'));
if($gdate==date("Y-m-d",strtotime('last day of december'))){
$queryrun=mysql_query( $query);
you were checking with d-m-Y
which is wrong. both date format wasn’t same and that the query is not running. and also a closing )
bracket was missing.
Note: mysql_query will be deprecated.
solved Can’t run MySQL query with an end of the year check [closed]