Problem using log in/log out privilege in website

[KlausVonKarma]

HELP! I'm a newbie in PHP and I'm stucked in coding for log in/logout using sessions.

 

 

How can I disable logging in when I am already logged in?

 

Also, how can I control what guests and admin can see in my website.

 

Thanks in advance !

[thara]

What have you tried so far?

[ignace]

How can I disable logging in when I am already logged in?

By simply checking if they are logged in. If they are simply redirect them to the screen they would go after logging in.

Also, how can I control what guests and admin can see in my website.

if ($user['is_admin'] == 1) {
  // can see it
} else {
  // can't see it
}

[KlausVonKarma]

I've tried simple log in like this one

 

<?php

$host="localhost"; // Host name 
$username="root"; // Mysql username 
$password=""; // Mysql password 
$db_name="dbadmin"; // Database name 
$tbl_name="tbladmin"; // 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");

// username and password sent from form 
$myusername=$_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";
}
?>

 

this is my check_login.php after that how can I enable/disable content which can be viewed by normal / admin users.

[KlausVonKarma]

 

By simply checking if they are logged in. If they are simply redirect them to the screen they would go after logging in.

if ($user['is_admin'] == 1) {
  // can see it
} else {
  // can't see it
}

 

 

This is what I've came up in the first place. But can I hide/show html codes with this. 

 

Btw, is that javascript?