方法一：

Open /app/design/adminhtml/default/default/template/catalog/product/edit.phtml and add the following code to the bottom of the file:

<?php$dbread = Mage::getSingleton('core/resource')->getConnection('core_read');$sql = $dbread->query("SELECT * FROM catalog_product_entity ORDER BY created_at DESC LIMIT 1");$res = $sql->fetch();
?>
<script type="text/javascript">
if(document.getElementById('sku').value == ""){document.getElementById('sku').value = <?php echo (int)$res["sku"] + 1; ?>;
}
</script>

Note:Read the SKU (must be an integer) of the last added product.
Increment the SKU by 1.
Pre-populate the incremented new SKU to the SKU field by JavaScript.

方法二：

打开 app/code/core/Mage/Adminhtml/controllers/Catalog/ProductController.php

line 743:

/*** Save product action*/
public function saveAction()
{$storeId        = $this->getRequest()->getParam('store');$redirectBack   = $this->getRequest()->getParam('back', false);$productId      = $this->getRequest()->getParam('id');  $isEdit         = (int)($this->getRequest()->getParam('id') != null);$data = $this->getRequest()->getPost();//===> 这里开始if(isset($data['category_ids']) AND $data['category_ids']) $category_ids = array_filter(array_unique(explode(',', $data['category_ids'])));if(!$category_ids) if($productId) $category_ids = array_filter(Mage::getModel('catalog/product')->load($productId)->getCategoryIds());$_categories = array();foreach ($category_ids as $category_id) {if($category_id){$_cat = Mage::getModel('catalog/category')->load($category_id);$_cat->getLevel()*1 == 2 ? $_categories[$_cat->getId()]['name'] = $_cat->getName() : $_categories[$_cat->getParentId()]['son'][$_cat->getId()] = $_cat->getName();}}$_first_category = current($_categories);if(!$_first_category) exit('<script>alert("Please Choose any Product Category !");history.back();</script>');if(!$productId OR ($productId AND !$data['product']['sku'])){$prefix = '';if(stripos('+'.$_first_category['name'], 'decals')) $prefix .= 'D-';if(isset($_first_category['son'])) $prefix .= strtoupper(substr($_first_category['name'], 0, 1).substr(current($_first_category['son']), 0, 1));else $prefix .= strtoupper(substr($_first_category['name'], 0, 2));$dbread                 =   Mage::getSingleton('core/resource')->getConnection('core_read');$sql                    =   $dbread->query("SELECT * FROM mgy2_catalog_product_entity WHERE `sku` LIKE '".$prefix."%' ORDER BY `entity_id` DESC LIMIT 1 ");$row                    =   $sql->fetch();$next_sku_num           =   abs(substr($row['sku'], -4)*1)+1;$next_sku_len           =   strlen($next_sku_num)*1;$next_sku               =   $prefix.($next_sku_len < 4 ? str_repeat('0',(4-$next_sku_len)) : '').$next_sku_num;$_POST['product']['sku'] =& $next_sku;}//===> 这里结束  if ($data) {$this->_filterStockData($data['product']['stock_data']);$product = $this->_initProductSave();// echo '<pre>'; print_r($data); echo '</pre>'; die;    try {$product->save();$productId = $product->getId();if (isset($data['copy_to_stores'])) {$this->_copyAttributesBetweenStores($data['copy_to_stores'], $product);}$this->_getSession()->addSuccess($this->__('The product has been saved.'));} catch (Mage_Core_Exception $e) {$this->_getSession()->addError($e->getMessage())->setProductData($data);$redirectBack = true;} catch (Exception $e) {Mage::logException($e);$this->_getSession()->addError($e->getMessage());$redirectBack = true;}}if ($redirectBack) {$this->_redirect('*/*/edit', array('id'    => $productId,'_current'=>true));} elseif($this->getRequest()->getParam('popup')) {$this->_redirect('*/*/created', array('_current'   => true,'id'         => $productId,'edit'       => $isEdit));} else {$this->_redirect('*/*/', array('store'=>$storeId));}
}

原理如下：

Wall decals
D-WA0001

Car decal
Bumper - D-CB0001
Car - D-CC0001
Mirror D-CM0001

MACBOOK DECALS
Macbook or Laptop - D-MM0001
Trackpad - D-MT0001

iPad
IPad - D-IP0001
IPad mini - D-IM0001

原理自己计算吧

原文/转自：Magento: 自动生成产品SKU Auto generated SKU when add product in magento