Este ejemplo debería ayudarlo un poco, pero recomiendo usar mysqli y es una muy mala idea almacenar sus contraseñas en texto sin formato. Debería considerar buscar mysqli, codificar contraseñas y comenzar a familiarizarse con php 5.4, ya que muchas de las funciones utilizadas aquí HAN cambiado y ya no son compatibles.
checklogin.php
<?php
$host="host"; // Host name
$username="username"; // Mysql username
$password="password"; // Mysql password
$db_name="database"; // Database name
$tbl_name="table"; // Table name
// Connect to server and select databse.
mysql_connect("$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'];
// Remove Magic Quotes
if (get_magic_quotes_gpc()){
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
}
$sql = sprintf(
"SELECT * FROM $tbl_name WHERE username='%s' and password='%s' LIMIT 1;",
mysql_real_escape_string($myusername),
mysql_real_escape_string($mypassword)
);
$result = mysql_query($sql);
// MySQL count
$count = mysql_num_rows($result);
if ($count){
$_SESSION['username'] = $myusername; // $_SESSION['loggedin'] = true or false would work too
$_SESSION['mypassword'] = $mypassword; // Why store the password in session data?
header("Location: login_success.php");
}else{
header("Location: main_login.php?msg=Login_Failed");
}
?>
login_success.php
<?php
session_start();
if (!isset($_SESSION['username']) || empty($_SESSION['username']){
header("Location: mail_login.php");
}
?>
<html>
<body>
Welcome <?php echo $_SESSION['username']; ?>
Login Successful
</body>
</html>
inicio_de_principal.php
<?php
if (isset($_GET['msg']) && !empty($_GET['msg']) echo $_GET['msg'];
?>
<table width="300" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#CCCCCC">
<tr>
<form name="form1" method="post" action="checklogin.php">
<td>
<table width="100%" border="0" cellpadding="3" cellspacing="1" bgcolor="#FFFFFF">
<tr>
<td colspan="3"><strong>Member Login </strong></td>
</tr>
<tr>
<td width="78">Username</td>
<td width="6">:</td>
<td width="294"><input name="myusername" type="text" id="myusername"></td>
</tr>
<tr>
<td>Password</td>
<td>:</td>
<td><input name="mypassword" type="text" id="mypassword"></td>
</tr>
<tr>
<td> </td>
<td> </td>
<td><input type="submit" name="Submit" value="Login"></td>
</tr>
</table>
</td>
</form>
</tr>
</table>
Úselo bajo su propio riesgo. :)
