magento直接运行如下sql语句，，即可得到。。然后自己保存下就行了。。。效果如下：

+-------------------+------------+
| sku               | categories |
+-------------------+------------+
| 1111              | 22         |
| 1112              | 22         |
| 1113              | 22         |
| 1114              | 22         |
| 1gbdimm           | 15,31      |
| 1tb7200           | 29         |
| 226bw             | 30         |
| 250gb5400         | 29         |
| 2gbdimm           | 15,31      |
| 384822            | 23         |
| 4fasd5f5          | 19         |
| 500gb5400         | 29         |
| 500gb7200         | 29         |
| 512dimm           | 15,31      |
| 750               | 12,26      |
| 8525PDA           | 8          |
+-------------------+------------+

这里的GROUP_CONCAT()函数少见但有用，它可以把多行记录，合并成一行。这在SQL中通常称为：行转列。

select c.sku
      ,GROUP_CONCAT(p.category_id SEPARATOR ',') as categories
  from catalog_product_entity as c
           inner join catalog_category_product as p
    on c.entity_id = p.product_id
 group by c.sku;