Getting the sum of sales per year MYSQL PHP - php

Question

I want to get the sales per year I have this code (please see below), that gets the column name and format it into (please see below). I have start date and end date I want to get the all the months between the two years. For example start date = 01/01/2017 and end date = 01/01/2018 I want go get the months between them and format it into SUM(JAN_2017) AS JAN_2017, etc and at the same time get the sum of all the months for the year 2017 and 2018.
SCREENSHOT OF MY TABLE
THIS IS MY COLUMN NAME SAMPLE (PLEASE REFER TO THE SCREENSHOT):
JAN_2017, FEB_2017 UPTO DEC_2017
SAMPLE OUTPUT OF MY CODE:
SUM(JAN_2017) AS JAN_2017, etc.
CODE:
$start = new DateTime($_POST["start"]);
$end = new DateTime($_POST["end"]);
$smonth = (int)$start->format('Y')*12+(int)$start->format('n');
$emonth = (int)$end->format('Y')*12+(int)$end->format('n');
$firstmonth = min($smonth, $emonth);
$lastmonth = max($smonth, $emonth);
$months = array();
for ($i = $firstmonth; $i <= $lastmonth; $i++) {
$thism = new DateTime(sprintf('%04d-%02d-01', intdiv($i, 12), $i % 12));
$months[] = strtoupper($thism->format('M_Y'));
}
$m_total = implode(',', preg_replace('/^(.*)$/', 'SUM($1) AS $1', $months));
$m_average = implode(',', preg_replace('/^(.*)$/', 'AVG($1) AS $1', $months)
);