gform_field_validation

add_filter("gform_field_validation_2_39", "custom_validation", 10, 4);
function custom_validation($result, $value, $form, $field) {

if ($result["is_valid"]) {
$tablename = "tbl6month";
//$tablename = "tbl2month";
$fieldname = "code";
//$filename = "2monthcode";

$link = mysql_connect('greenkidcraftscom.fatcowmysql.com', 'greenkidcrafts', '*password*');
if (!$link) {
$result["is_valid"] = false;
$result["message"] = 'Could not connect: ' . mysql_error();
} else {
mysql_select_db("plumdistrict01");


$query = sprintf("SELECT * FROM %s
WHERE %s='%s'",
mysql_real_escape_string($tablename),
mysql_real_escape_string($fieldname),
mysql_real_escape_string(trim($value)));
$dbresult = mysql_query($query);

if (!$dbresult) {
$message = 'Invalid query: ' . mysql_error() . "\n";
$message .= 'Whole query: ' . $query;
$result["is_valid"] = false;
$result["message"] = $message;
} else {
if (mysql_num_rows($dbresult) < 1) {
$result["is_valid"] = false;
$result["message"] = "Please enter a valid discount code";
}
}
}
}

return $result;
}