PHP查询在我的HTML页面中没有出现任何结果

Question

我正在尝试通过php查询在HTML页面上显示我的SQL数据库中的数据。

之前我以同样的方式完成了类似的查询，但是这个查询在我的html页面上没有显示任何结果，我不明白为什么。

<?php 
$con=mysqli_connect("localhost","root","password","registration"); 
if (mysqli_connect_errno()) 
{ 
    die("Failed to connect to MySQL: " . mysqli_connect_error()); 
}

$query = "SELECT * FROM goal WHERE id = $_SESSION[userid]";
$result = mysqli_query($con, $query);

if($result == false) {
die("Query failed: ".mysqli_error($con).PHP_EOL.$query);
}

while($row = mysqli_fetch_assoc($result))  
{ 
    echo "Weight Lost:"."<p>".$row['weightlost']."</p>\n";
    echo "Weight Unit:"."<p>".$row['weightunit']."</p>\n";
    echo "Date set for goal to be reached:"."<p>".$row['whenby']."</p>\n";

} 
mysqli_close($con);

?>