Muliple type user login on same form in PHP

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PHP

<?php
if(isset($_POST['submit']) {
ob_start();
$id=$_POST['id'];
$pswd=$_POST['pswd'];

$sql="SELECT * FROM admin WHERE id=........."
$query=mysql_query($sql);
$count=mysql_num_rows($query);
if($count==1) {
header('location: admin/index.php');
} else {
$sql="SELECT * FROM user WHERE id=........."
$query=mysql_query($sql);
$count=mysql_num_rows($query);
if($count==1) {
header('location: user/index.php');
} else {
echo 'Invalid id-password combination';
}
}
}
?>

is any errors on this code???

What I have tried:

help me pleaseeeeeeeeeeeeeeeee