如何通过Group Id计算php中SQL列的平均值并在HTML页面上显示？

Question

I want to calculate the Average value of all other columns grouping them by collegename. i.e RVCE with Average of all other columns, BMS with Average of all other columns and so on and display the value in HTML.

SQL Database Structure Image

I have tried the following code in but it is returning me no values.

<?php
$hostname="localhost:8889";
$username="root";
$password="root";
$db = "rank";
$dbh = new PDO("MySQL:host=$hostname;dbname=$db", $username, $password);
foreach($dbh->query('SELECT collegename,AVG(campus)  
FROM college       
GROUP BY collegename') as $row) {
echo "<tr>";
echo "<td>" . $row['AVG(campus)'] . "</td>";
echo "</tr>";
}
?>

Answer 1

Try this one?

<?php
$hostname="127.0.0.1";
$port=8889;
$username="root";
$password="root";
$db = "rank";
$dbh = new PDO("mysql:dbname=$db;host=$hostname;port=$port", $username, $password);
foreach($dbh->query('SELECT collegename,AVG(campus) AS avg_campus  
FROM college       
GROUP BY collegename') as $row) {
echo "<tr>";
echo "<td>" . $row['collegename'] . " AVG: " . $row['avg_campus'] . "</td>";
echo "</tr>";
}
?>