I understand `mysql_` has been deprecated, but I'm just using it as a tool to learn from a book.

I'm trying to learn about placeholders and I got the following error when I clicked on "add record":

```
INSERT failed: EXECUTE statement USING @first,@last,@email,@user 
Unknown prepared statement handler (statement) given to EXECUTE

```

using the following code:

```
if (isset($_POST['first']) && isset($_POST['last']) && isset($_POST['user_name']) && isset($_POST['email']))
{
    $first      = get_post('first');
    $last       = get_post('last');
    $email      = get_post('email');
    $user_name      = get_post('user_name');

    // begin placeholde code
    $query = 'PREPARE statement FROM "INSERT INTO user_master VALUES(?,?,?,?)"';
    mysql_query($query);

    $query = 'SET @first = "$first",' . 'SET @last = "$last",' . 'SET @email = "$email",' . 'SET @user_name = "$user_name",';
    mysql_query($query);

    $query = 'EXECUTE statement USING @first,@last,@email,@user';
    mysql_query;

    // end placeholder code

    if(!mysql_query($query, $db_server)) echo "INSERT failed: $query <br />" . mysql_error() . "<br /><br />";
}

echo <<<END
<form action = "willingLog.html" method="post"><fieldset><legend>Sign Up:</legend>    <pre>
    First       <input type="text" name="first" />
    Last        <input type="text" name="last" />
    Email       <input type="text" name="email" />
    Username    <input type="text" name="user_name" />
                <input type="submit" value="AD RECORD" />
</pre></fieldset></form>
END;

// also from placeholder code
$query = 'DEALLOCATE PREPARE statement';
mysql_query($query);
// end placeholder code

```