PHP gets the code of last week, this week, last month, this month, this quarter, and last quarter

 echo date("Ymd",strtotime("now")), "\n";
 echo date("Ymd",strtotime("-1 week Monday")), " \n";
 echo date("Ymd",strtotime("-1 week Sunday")), "\n";
 echo date("Ymd",strtotime("+0 week Monday")), "\n" ";
 echo date("Ymd",strtotime("+0 week Sunday")), "\n";

 echo "**********The month:";
 echo date( 'n');
 echo "************Day of the week:";
 echo date("w");
 echo "************Day of the month:" ;
 echo date("t");
 echo "*******";

 echo 'Last week's start time:';
 echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m"),date("d")-date("w")+1-7,date("Y")))," \n";
 echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("d")-date("w")+7-7, date("Y"))),"\n";
 echo 'Start time of this week:';
 echo date("Y-m-d H:i:s",mktime(0, 0, 0,date("m"),date("d")-date("w")+1,date("Y"))),"\n";
 echo date("Y-m-d H:i :s",mktime(23,59,59,date("m"),date("d")-date("w")+7,date("Y"))),"\n";

 echo 'Start time of last month:';
 echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m")-1,1 ,date("Y"))),"\n";
 echo date("Y-m-d H:i:s",mktime(23,59,59,date("m") ,0,date("Y" ))),"\n";
 echo 'Start time of this month:';
 echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date ("m"),1,date("Y"))),"\n";
 echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"), date("t"),date("Y"))),"\n";

 $season = ceil((date('n'))/3);//What quarter is this month
 echo ' Start time of this quarter:';
 echo date('Y-m-d H:i:s', mktime(0, 0, 0,$season*3-3+1,1,date( 'Y'))),"\n";
 echo date('Y-m-d H:i:s', mktime(23,59,59,$season*3,date('t',mktime(0, 0, 0,$season*3,1,date("Y"))),date('Y'))),"\n";

 $season = ceil((date('n'))/3) -1; //Which quarter is the last quarter? echo 'Start time of last quarter:';
 echo date('Y-m-d H:i:s', mktime(0, 0, 0 ,$season*3-3+1,1,date('Y'))),"\n";
 echo date('Y-m-d H:i:s', mktime(23,59,59,$season* 3,date('t',mktime(0, 0, 0,$season*3,1,date("Y"))),date('Y'))),"\n";
?>

PHP