mysql test

<?php
    /**
     * @sqltest.php 
     */
require_once "app_config.php";
if (isset($_POST['delete']) && isset($_POST['isbn'])) {

    $isbn=get_post('isbn');
    $query="delete from classics where isbn='$isbn'";

    if (!mysql_query($query)) {
        echo mysql_error();        
    }
}
if(isset($_POST['author']) &&isset($_POST['title']) && isset($_POST['category']) && isset($_POST['year']) && isset($_POST['isbn'])){
    $author=get_post("author");
    $title=get_post("title");
    $category=get_post("category");
    $year=get_post("year");
    $isbn=get_post("isbn");
    $query="insert into classics values('$author','$title','$category','$year','$isbn')";
    if(!mysql_query($query)){
        echo mysql_error();
    }
}
echo <<<_END
<form action="sqltest.php" method="post"><pre>
    Author:<input type="text" name="author"/>
    Title:<input type="text" name="title"/>
    Category:<input type="text" name="category"/>
    Year:<input type="text" name="year"/>
    ISBN:<input type="text" name="isbn"/>
    <input type="submit" name="ADD RECORD"/></pre>
</form>
_END;
$query="select * from classics";
$result=mysql_query($query);

if (!$result) die(mysql_error());
$rows=mysql_num_rows($result);
for($j=0;$j<$rows;++$j){
    $row=mysql_fetch_row($result);
echo <<<_END
<pre>
Author $row[0]
Title $row[1]
Category $row[2]
Year $row[3]
ISBN $row[4]
</pre>
<form actio="sqltest.php" method="post">
    <input type="hidden" name="delete" value="yes"/>
    <input type="hidden" name="isbn" value="$row[4]"/>
    <input type="submit" value="DELETE RECORD"/>
</form>
_END;
}
mysql_close();
function get_post($var){
    return mysql_real_escape_string($_POST[$var]);
}
?>