我在具有MySQL的WAMP服务器上拥有此PHP代码，并且当我访问该站点时，此错误出现在对话框中。我怎样才能解决这个问题？
<?php
// Create connection
$con = mysqli_connect("localhost","userdb","userdb","apptestdb");
// Check connection
if (mysqli_connect_errno($con))
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
// This SQL statement selects ALL from the table 'Locations'
$sql = "SELECT * FROM Locations";
// Check if there are results
if ($result = mysqli_query($con, $sql))
{
// If so, then create a results array and a temporary one
// to hold the data
$resultArray = array();
$tempArray = array();
// Loop through each row …