如何使用此腳本計算銷售稅？

Question

我使用的是前段時間我遇到的教程中的購物車腳本，我需要修改它來計算我的州（賓夕法尼亞州）的銷售稅。我希望它提取狀態，將它與賓夕法尼亞州或賓夕法尼亞州進行比較，因爲有人寫狀態簡寫，然後將小計（對於項目......在發貨前添加）乘以該州的銷售稅並將其添加到小計。我應該如何去做這件事？這是用於總計算的腳本。

<?php 
require_once 'config.php'; 

/********************************************************* 
*     CHECKOUT FUNCTIONS 
*********************************************************/ 
function saveOrder() 
{ 
    $orderId  = 0; 
    $shippingCost = 5; 
    $requiredField = array('hidShippingFirstName', 'hidShippingLastName', 'hidShippingAddress1', 'hidShippingCity', 'hidShippingPostalCode', 
          'hidPaymentFirstName', 'hidPaymentLastName', 'hidPaymentAddress1', 'hidPaymentCity', 'hidPaymentPostalCode'); 

    if (checkRequiredPost($requiredField)) { 
     extract($_POST); 

     // make sure the first character in the 
     // customer and city name are properly upper cased 
     $hidShippingFirstName = ucwords($hidShippingFirstName); 
     $hidShippingLastName = ucwords($hidShippingLastName); 
     $hidPaymentFirstName = ucwords($hidPaymentFirstName); 
     $hidPaymentLastName = ucwords($hidPaymentLastName); 
     $hidShippingCity  = ucwords($hidShippingCity); 
     $hidPaymentCity  = ucwords($hidPaymentCity); 

     $cartContent = getCartContent(); 
     $numItem  = count($cartContent); 

     // save order & get order id 
     $sql = "INSERT INTO tbl_order(od_date, od_last_update, od_shipping_first_name, od_shipping_last_name, od_shipping_address1, 
             od_shipping_address2, od_shipping_phone, od_shipping_state, od_shipping_city, od_shipping_postal_code, od_shipping_cost, 
             od_payment_first_name, od_payment_last_name, od_payment_address1, od_payment_address2, 
             od_payment_phone, od_payment_state, od_payment_city, od_payment_postal_code) 
       VALUES (NOW(), NOW(), '$hidShippingFirstName', '$hidShippingLastName', '$hidShippingAddress1', 
         '$hidShippingAddress2', '$hidShippingPhone', '$hidShippingState', '$hidShippingCity', '$hidShippingPostalCode', '$shippingCost', 
         '$hidPaymentFirstName', '$hidPaymentLastName', '$hidPaymentAddress1', 
         '$hidPaymentAddress2', '$hidPaymentPhone', '$hidPaymentState', '$hidPaymentCity', '$hidPaymentPostalCode')"; 
     $result = dbQuery($sql); 

     // get the order id 
     $orderId = dbInsertId(); 

     if ($orderId) { 
      // save order items 
      for ($i = 0; $i < $numItem; $i++) { 
       $sql = "INSERT INTO tbl_order_item(od_id, pd_id, od_qty) 
         VALUES ($orderId, {$cartContent[$i]['pd_id']}, {$cartContent[$i]['ct_qty']})"; 
       $result = dbQuery($sql);      
      } 


      // update product stock 
      for ($i = 0; $i < $numItem; $i++) { 
       $sql = "UPDATE tbl_product 
         SET pd_qty = pd_qty - {$cartContent[$i]['ct_qty']} 
         WHERE pd_id = {$cartContent[$i]['pd_id']}"; 
       $result = dbQuery($sql);      
      } 


      // then remove the ordered items from cart 
      for ($i = 0; $i < $numItem; $i++) { 
       $sql = "DELETE FROM tbl_cart 
         WHERE ct_id = {$cartContent[$i]['ct_id']}"; 
       $result = dbQuery($sql);      
      }       
     }     
    } 

    return $orderId; 
} 

/* 
    Get order total amount (total purchase + shipping cost) 
*/ 
function getOrderAmount($orderId) 
{ 
    $orderAmount = 0; 

    $sql = "SELECT SUM(pd_price * od_qty) 
      FROM tbl_order_item oi, tbl_product p 
      WHERE oi.pd_id = p.pd_id and oi.od_id = $orderId 

      UNION 

      SELECT od_shipping_cost 
      FROM tbl_order 
      WHERE od_id = $orderId"; 
    $result = dbQuery($sql); 

    if (dbNumRows($result) == 2) { 
     $row = dbFetchRow($result); 
     $totalPurchase = $row[0]; 

     $row = dbFetchRow($result); 
     $shippingCost = $row[0]; 

     $orderAmount = $totalPurchase + $shippingCost; 
    } 

    return $orderAmount;  
} 

?> 

Answer 1

您不必爲每個城市處理不同的稅率？通常這可以通過郵政編碼在稅表中查找，甚至可以用於街道地址+郵政編碼（在某些州）。

它應該是這樣的：

// is it a Pennsylvania zip code? 
if ($zipcode < 15000 || $zipcode > 19699) // needs verification of the actual range 
    $taxrate = 0; 
else 
{ 
    $rs = mysql_query ("select rate from taxtable where zipcode = '$zipcode'", $db); 
    if (!$rs) 
    { 
     // error looking up rate, maybe apply a default? 
    } 
    else 
    { 
     $row = mysql_fetch_assoc($rs); 
     $taxrate = $row['rate']; 
    } 
} 

$amount = $amount * (1 + $taxrate/100.0);