Undefined index in php.

whenever i run this code i got error "undefined index" give me a solution or tell me what i have to do.

code:

<?php
$a=$_POST['name'];
$b=$_POST['password'];
$con=mysql_connect("localhost","root","root");

mysql_select_db("login",$con);

$res= mysql_query("select * from login where ID ='$a' AND PASS ='$b' ");

if(mysql_num_rows($res)=='1')

echo "YOU ARE A MEMBER";
else "incorrect id or password";

?>

 

*
if(mysql_num_rows($res)=='1'){
echo "YOU ARE A MEMBER";}
else {echo "incorrect email id or password";}

 

Which line exactly does it give the error? Can you paste here the exact error? I don't see any problem as far as I can see.

 

Roshaan.N is right, but I guess your problem is somewhere at this line
$res= mysql_query("select * from login where ID ='$a' AND PASS ='$b' ");
check your DB field is same as you are mentioning in your query.

 

check your table for an index