MySQL将用户输入的信息输入到表中

在我的网站上，我有一个PHP脚本，当用户在表单中输入"用户名"answers"密码"时，它会检查MySQL表中是否存在用户名和密码，并将用户传递到网站主页上。我的问题是：当用户向表单中输入信息时，有没有办法向表中添加行下面是上面描述的php页面。有没有办法修改这个脚本以允许用户输入行？

<?php
ob_start();
$host="--------"; // Host name 
$username="-------"; // Mysql username 
$password="--------"; // Mysql password 
$db_name="--------"; // Database name 
$tbl_name="-------"; // Table name 
// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
mysql_select_db("$db_name")or die("cannot select DB");
// Define $myusername and $mypassword 
$myusername=$_POST['myusername']; 
$mypassword=$_POST['mypassword']; 
// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);
$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);
// Mysql_num_row is counting table row
$count=mysql_num_rows($result);
// If result matched $myusername and $mypassword, table row must be 1 row
if($count==1){
// Register $myusername, $mypassword and redirect to file "login_success.php"
session_register("myusername");
session_register("mypassword"); 
header("location:login_success.php");
}
else {
echo "Wrong Username or Password";
}
ob_end_flush();
?>

非常感谢您的帮助