How to count amount of students per university - php

Question

I have a SQL database of university students, with the following details:
Table_name: register
Column_names: position, tertinst
The data in the database will look something like this:
Coach..........UCT
Athlete........Tukkies
Official.......University of JHB
Athlete........Tukkies
Athlete........Tshwane Tech
Manager........UCT
I need to count the amount of students who are athletes(position), per university(tertinst) and the output has to be something like this:
UCT.....................735
University of Jhb.......668
Tukkies.................886
this is my attempt:
$positionx = 'Athletes';
include_once 'core/includes/db_connect.php';
$sql = "SELECT tertinst, COUNT(position) FROM register WHERE position = '$positionx' GROUP BY tertinst ";
$result = $conn->query($sql);
while ($row = mysql_fetch_array($result)) {
echo $row['COUNT(tertinst)'] . '......' . $row['COUNT(position)'];
}
$conn->close();
I get no result when the code is executed and I have searched for a different solution for hours, without success.

Answer 1

I made a few mistakes, and corrected the syntax in the sql count, as well as the echo. Here is the solution to my problem:
<?php
include_once 'core/includes/db_connect.php';
$sql = "SELECT tertinst, COUNT(*) total FROM register WHERE position = 'Athletes' GROUP BY tertinst ";
$result = $conn->query($sql);
while ($row = $result->fetch_assoc()) {
$tertinst = $row["tertinst"];
echo $tertinst . '......' . $row['total'] . '<br>';
}
$conn->close();