如何在MySQL中处理动态列

Question

I have a site that has different type of products with different specifications for each of them.

I want to be able to use only one products table with a set of columns but because columns are different depending on what type, I have to create multiple products table catering for each type. This I think is time consuming and not really effective way to manage as an ongoing solution.

Is there a good way to manage this type of scenario with the database?

I'm using Cakephp as the framework.

Answer 1

规范化您的数据结构：例如，拥有一个product_info表（FK放入products表中），其中包含列key和value以表示有关每个产品的附加信息。

Answer 2

Martin Fowler lists three general approaches.

• Single table - Putting all the columns in one table and only using the ones you need (this sounds the closest to what you have)
• Class table - All classes have their own table storing data specific to that class (with the same primary key in every relevant table)
• Concrete table - The same as above, but only concrete classes have tables, not abstract ones.

Single table is the simplest unless you have a good reason not to - just have all possible fields there, and only use the ones you need in each class. You do have the disadvantage of not being able to enforce NOT NULL; if this matters, either make a custom constraint depending on the type of object, or use option 2 or 3.

Answer 3

I wrote about using the EAV model with cake a little while ago, I think this post might be helpful, but slightly outdated. http://nuts-and-bolts-of-cakephp.com/2010/07/27/keyvalue-tables-and-how-to-use-them-in-cakephp-1-3/

Also, this could be very helpful for your particular question... Please take a look and study some concepts in Magento (a very popular PHP-based ecommerce framework) makes heavy use of EAV schemas and does a nice job of indexing and flattening the data.

You can certainly gain a lot of interesting perspective on EAV implementation. Whether you love it or not is a different story :)