Du vil gøre følgende:
$dupesql = "SELECT * FROM table where (name = '$name' AND description = '$description' AND manufacturer = '$manufacturer' AND city ='$city' AND price = '$price' AND enddate = '$end_date')";
$duperaw = mysql_query($dupesql);
if (mysql_num_rows($duperaw) > 0) {
//your code ...
}
Se Her for mere information.