在php中从数据库读取值时出错

I'm trying this code through which I'm getting the connection but I'm getting an error undefined variable.

Connected to MySQL
SELECT * FROM headcont;
Notice: Undefined variable: myQuery in C:\xampp\htdocs\Myweb\index.php on line 86
No database selected

require("connection.php");

if($con)
{
    $qry="SELECT * FROM headcont;";
    //mysql_select_db('content');
    echo $qry;
    $result=mysql_query($qry) or die($myQuery."<br/><br/>".mysql_error());

    while($row=mysql_fetch_assoc($result))
    {
            $title=$row[title];
            $desc=$row[description];
            echo $title;

        }
    }

I don't know what the issue is, can someone please help me with this?

require("connection.php");

if($con)
{
    $qry="SELECT * FROM headcont;";
    mysql_select_db('content');
    echo $qry;
    $result=mysql_query($qry) or die($myQuery."<br/><br/>".mysql_error());

    while($row=mysql_fetch_assoc($result))
    {
            $title=$row[title];
            $desc=$row[description];
            echo $title;

        }
    }

<?php
require("connection.php");

$query = mysql_query("SELECT * FROM `headcont` ") or die(mysql_error());

while ($row = mysql_fetch_array($query)) {
 $title = $row['title'];
 $desc = $row['description'];
 echo $title;
}
?>