一重引用符を処理すると、PHP MySQL の挿入が一貫して失敗するのはなぜですか?

$result = mysql_query("INSERT INTO job_log
(order_id, supplier_id, category_id, service_id, qty_ordered, customer_id, user_id, salesperson_ref, booking_ref, booking_name, address, suburb, postcode, state_id, region_id, email, phone, phone2, mobile, delivery_date, stock_taken, special_instructions, cost_price, cost_price_gst, sell_price, sell_price_gst, ext_sell_price, retail_customer, created, modified, log_status_id)
VALUES
('$order_id', '$supplier_id', '$category_id', '{$value['id']}', '{$value['qty']}', '$customer_id', '$user_id', '$salesperson_ref', '$booking_ref', '$booking_name', '$address', '$suburb', '$postcode', '$state_id', '$region_id', '" . mysql_real_escape_string($email) . "', '" . mysql_real_escape_string($phone) . "', '" . mysql_real_escape_string($phone2) . "', '" . mysql_real_escape_string($mobile) . "', STR_TO_DATE('$delivery_date', '%d/%m/%Y'), '$stock_taken', '" . mysql_real_escape_string($special_instructions) . "', '$cost_price', '$cost_price_gst', '$sell_price', '$sell_price_gst', '$ext_sell_price', '$retail_customer', '".date('Y-m-d H:i:s', time())."', '".date('Y-m-d H:i:s', time())."', '1')");

$query = mysql_query("INSERT INTO message_log
(order_id, timestamp, message_type, email_from, supplier_id, primary_contact, secondary_contact, subject, message_content, status)
VALUES
('$order_id', '".date('Y-m-d H:i:s', time())."', '$email', '$from', '$row->supplier_id', '" . mysql_real_escape_string($row->primary_email) . "', '" . mysql_real_escape_string($row->secondary_email) . "', '" . mysql_real_escape_string($subject) . "', '" . mysql_real_escape_string($message_content) . "', '1')");