<?php
$var = $_POST['bookid'];
if(isset($var)) {

$con = mysql_connect("localhost","root","1234");
mysql_select_db("library");
$bookinfo = mysql_query("SELECT * FROM books WHERE bookid='$var';");
while($row = mysql_fetch_array($bookinfo))
{
echo $row['bookid'] . "-" . $row['id'];
}
}
echo "Test echo";
?>