grepper add code answer
variable in cakephp3 counting summming up
$payment_tbl = TableRegistry:: getTableLocator()->get(“MembershipPayment”);
$payment = $payment_tbl->find();
$payment->select( ['totalpmnt' => $payment->func()->sum('yoursumfield here') ]);
$this->set('payment',$payment->totalpmnt);
then in view
echo $payment;
should contain the sum.
or, if you do
$this->set('payment', $payment);
you need to do in your view:
echo $payment->totalpmnt;
or
<?= $payment->totalpmnt ?>