ต้องการหาค่า % เปรียบเทียบเดือนเดียวกัน เช่น $ผลรวม=ปีปัจุบัน-ปีก่อนหน้า*100/ปีก่อนหน้า

select cur_y, count_cur, count_old, (count_cur - count_old) / 100 * count_old as total
from (
	select cur_y, count(tb1.field) as count_cur, count(tb2.field) as count_old
	from (select year(fielddate) as cur_y, (year(fielddate)-1) as old_y from tablename group by year(fielddate)) as yy
	left join tablename tb1 on year(tb1.fielddate) = yy.cur_y
	left join tablename tb2 on year(tb2.fielddate) = yy.old_y
	group by cur_y
) as tmp
order by cur_y

<?php
          function days_in_month($month, $year)
            {
           // calculate number of days in a month
         return $month == 2 ? ($year % 4 ? 28 : ($year % 100 ? 29 : ($year % 400 ? 28 : 29))) :(($month - 1) % 7 % 2 ? 30 : 31);
            }   

            $nowYear = date('Y');
            $startYear = 2549-543;
    
                for($year=$nowYear;$year>=$startYear;$year--) 
                {   
                    
                    echo  "<tr>";
                    echo  "<td><b>".($year+543)."</b></td>";

                    for($month=1;$month<=12;$month++)
                    {
                         $dmonth =cal_days_in_month(CAL_GREGORIAN, $month, $year); 
                        
                    $strSQL= "SELECT COUNT(VN) (count_cur - count_old) * 100 / count_old as total
                            FROM 
                                (SELECT COUNT (VN) dbo.HNOPD_MASTER.VN as count_cur, COUNT(dbo.HNOPD_MASTER.VN) as count_old FROM 
                                    (SELECT ".$year." as cur_y, (".$year.")-1) as old_y FROM dbo.HNOPD_MASTER GROUP BY ".$year." as yy
                                        LEFT JOIN dbo.HNOPD_MASTER on ".$year."(dbo.HNOPD_MASTER.VN) = yy.cur_y
                                        LEFT JOIN dbo.HNOPD_MASTER on ".$year."(dbo.HNOPD_MASTER.VN) = yy.old_y
                                GROUP BY cur_y
                            ) as tmp
                            ORDER BUY cur_y";  
                    $objExec = odbc_exec($conn,$strSQL) or die ("Error SQL [".$strSQL."]");
                        while($objResult = odbc_fetch_object($objExec))
                        {
                                $total=$objResult->total;  
                                echo "<td span class=border>".(number_format($total))."<br></td>";
                        } 
                        echo $strSQL;
                        }
                    echo "</tr>";
                    $nowYear--;
                }
?>

select 
	cur_y, 
	count_cur, 
	count_old, 
	(count_cur - count_old) * count_old / 100 as total
from (
	select 
		cur_y, 
		count(tb1.field) as count_cur, 
		count(tb2.field) as count_old
	from (
		select
			year(fielddate) as cur_y, 
			(year(fielddate)-1) as old_y 
		from tablename 
		group by year(fielddate)
	) as yy
	left join tablename tb1 on year(tb1.fielddate) = yy.cur_y
	left join tablename tb2 on year(tb2.fielddate) = yy.old_y
	group by cur_y
) as tmp
where ............................................
order by cur_y

select
	cur_y, 
	count(case month(tb1.fieldate) when 1 then 1 else null end) as cur_jan, 
	count(case month(tb1.fieldate) when 2 then 1 else null end) as cur_feb,
 	.....
	count(case month(tb2.fieldate) when 1 then 1 else null end) as old_jan, 
	count(case month(tb2.fieldate) when 2 then 1 else null end) as old_feb,