对于上面您所有的每个模块脚本，您可能会有三个(或更多)不同的成本分类：便宜的、一般的、昂贵的。
For each modular script you have above, you might have three (or more) different cost classifications: cheap, average, expensive.
因此，对于每个请求都通过查询数据库获取最新的分类列表是很浪费的。
Therefore, it would be wasteful to query a database on every request to get the latest list of categories.
注：为了达到这个目的，这里在“滥用”分类有一些弊点：对于每个条目只允许有一个分类。
Note: There is a drawback in 'misusing' the category field for this purpose: Only one category is allowed per item.
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