***的和最常见的答案是：选项B - 关系表用户表具有以下字段加入

The best and most common answer would be: choice B - Relational Table joined on user table with the following fields.

id
order
user_id
desc
photo_url_800
photo_url_150
photo_url_45
date_uploaded

或混合，其中，您分别保存的文件名，并与您的业务逻辑层添加的照片目录。

Or a hybrid, wherein, you store the file names individually and add the photo directory with your business logic layer.

我的分析，你的第一个选项是一个不好的做法。逗号分隔的字段是不可取的数据库。这将是很难为你更新这些领域并在其上添加描述。

My analysis, your first option is a bad practice. Comma separated fields are not advisable for database. It would be difficult for you to update these fields and add description on it.

关于表的优化，你可能想看看这些文章：

Regarding the table optimization, you might want to see these articles:

• 优化MyISAM数据查询


• 优化InnoDB的查询

• Optimizing MyISAM Queries
• Optimizing InnoDB Queries