我试图找到插入表中的一组成绩的GPA，成绩列为varchar类型，我需要循环遍历然后将其转换为十进制，我非常迷失，现在不知道如何进行此操作。任何帮助，将不胜感激
这是我到目前为止的东西，我不断收到错误消息：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Display GPA</title>
</head>
<body>
<?php
$host="XXXX";
$username="XXXX"; // Mysql username
$password="XXX"; // Mysql password
$db_name="XXXX"; // Database name
$tbl_name="gpa"; // Table name
// Connect to server and select databse.
$con=mysqli_connect("$host", "$username", "$password")or die("cannot connect");
mysqli_select_db($con,"bparis") or die ("no database");
if(mysqli_connect_errno())
$con = false;
if(!$con) {
echo "Failed to connect to database server!";
}
else {
$result = mysqli_query($con,"SELECT grade FROM gpa");
while ($row = mysql_fetch_array($result, MYSQL_NUM)) { …