Example: the user fills in everything but the product name.

I need to search on what is supplied, so in this case everything but productName=

This example could be for any combination of input.

Is there a way to do this?

Thanks.

    $name = $_POST['n'];
    $cat = $_POST['c'];
    $price = $_POST['p'];

if( !($name) )
{
    $name = some character to select all?
}


$sql = "SELECT * FROM products WHERE productCategory='$cat' and   
productName='$name' and productPrice='$price' ";

EDIT
Solution does not have to protect from attacks. Specifically looking at the dynamic part of it.