problem solved nimetumia hizi
<?php
$con=mysqli_connect("localhost","root","","online");
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$sql="SELECT product,username FROM registration where product='laptop'";
if ($result=mysqli_query($con,$sql))
{
// Return the number of rows in result set
$rowcount=mysqli_num_rows($result);
printf("bids:%d .\n",$rowcount);
// Free result set
mysqli_free_result($result);
}
mysqli_close($con);
?>