$month = date("m",strtotime($mydate));
date('m',strtotime('2018-06-30' )) == date('m');
You can use date_parse to parse almost any date format into its components. For example:
$date = date_parse("2012-01-02");
var_dump($date);
Will output:
array(12) {
["year"]=>
int(2012)
["month"]=>
int(1)
["day"]=>
int(2)
["hour"]=>
bool(false)