$month = '01';
$year = '2023';
$max_day = cal_days_in_month(CAL_GREGORIAN, $month, $year); //当月最后一天
$min = $year.'-'.$month.'-01 00:00:00';
$max = $year.'-'.$month.'-'.$max_day.' 23:59:59';
$sql = "select t.enterdate,count(*) as total_num,sum(t.total_price) as amount (select date_format(enterdate,'%e') as enterdate,total_price from orders where enterdate between {$min} and {$max}) t group by t.enterdate order by t.enterdate";
$return = mysqli_query($sql);