我在培训/学校领域工作过，我想我要指出的是，在你所说的“会话”(给定课程的实例)和课程本身之间通常存在M:1的关系。换句话说，你的目录提供了这门课程(“西班牙语101”之类的)，但你可能在一个学期中有两个不同的实例(Tu-Th由Smith教授，wed - friday由Jones教授)。

除此之外，这看起来是个不错的开始。我敢打赌，您会发现客户端域(指向“客户端”的图形)比您所建模的要复杂得多，但在获得一些实际数据来指导您之前，不要过于复杂。

这不是过度设计，这是我处理问题的方式。加入很好，不会有太大的性能损失(这是完全必要的，除非你对数据库进行反规格化，这是不建议的!)对于状态，查看是否可以使用枚举数据类型来优化该表。

以下是基于商业智能/报告专家和战略/规划经理角色的评论:

I agree with Larry's direction above. IMHO, It's not so much over engineered, some things just look a little out of place. To keep it simple, I would tag client directly to a Company ID, Department Description, Division Description, Department Type ID, Division Type ID. Use Department Type ID and Division Type ID as references to lookup tables and internal reporting/analysis fields for long term consistency. Packs table contains "Credit" column, shouldn't that actually be tied to the Client base table so if they many packs you can see how much credit owed is left for future classes? The application can take care of the calc and store it centrally in the Client table. Company info could use many more fields, including the obvious address/phone/etc. information. I'd also be prepared to add in D&B "DUNs" columns (Site/Branch/Ultimate) long term, Dun and Bradstreet (D&B) has a huge catalog of companies and you'll find later down the road their information is very helpful for reporting/analysis. This will take care of the multiple division issue you mention, and allow you to roll up their hierarchy for sub/division/branches/etc. of large corps. You don't mention how many records you'll be working with which could imply setting yourself up for a large development initiative which could have been done quicker and far fewer headaches with prepackaged "reporting" software. If your not dealing with a large database (< 65000) rows, make sure MS-Access, OpenOffice (Base) or related report/app dev solutions couldn't do the trick. I use Oracle's free APEX software quite a bit myself, it comes with their free database Oracle XE just download it from their site. FYI - Reporting insight: for large databases, you typically have two database instances a) transaction database for recording each detailed record. b) reporting database (data mart/data warehouse) housed on a separate machine. For more information search google both Star Schema and Snowflake Schema.

的问候。

我想到了几件事:

The tables seemed geared to reporting, but not really running the business. I would think when a client signs up, there's essentially an order being placed for the client attending a list of sessions, and that order might be for multiple employees in one company. It would seem an "order" table would really be at the center of your system and driving your data capture and eventual reporting. (Compare the paper documents you've been using to run the business with your database design to see if there's a logical match.) Companies often don't have divisions. Employees sometimes change divisions/departments, maybe even mid-session. Companies sometimes add/delete/rename divisions/departments. Make sure the possible realtime changing contents of your tables doesn't make subsequent reporting/grouping difficult. With so much contact data split over so many tables, you might have to enforce very strict data entry validation to keep your reports meaningful and inclusive. Eg, when a new client is added, making sure his company/division/department/city match the same values as his coworkers. The "packs" concept isn't clear at all. Since you indicate it's a small business, it would be surprising if performance would be an issue, considering the speed and capacity of current machines.

I want to address only the concern that joining to mutiple tables will casue a performance hit. Do not be afraid to normalize because you will have to do joins. Joins are normal and expected in relational datbases and they are designed to handle them well. You will need to set PK/FK relationships (for data integrity, this is important to consider in designing) but in many databases FKs are not automatically indexed. Since they wil be used in the joins, you will definitelty want to start by indexing the FKS. PKs generally get an index on creation as they have to be unique. It is true that datawarehouse design reduces the number of joins, but usually one doesn't get to the point of data warehousing until one has millions of records needed to be accessed in one report. Even then almost all data warehouses start with a transactional database to collect the data in real time and then data is moved to the warehouse on a schedule (nightly or monthly or whatever the business need is). So this is a good start even if you need to design a data warehouse later to improve report performance.

我不得不说你的设计对于一个计算机科学的大一学生来说是令人印象深刻的。

顺便说一句，值得注意的是，如果您已经在生成csv并希望将它们加载到mySQL数据库中，load DATA LOCAL INFILE是您最好的朋友:http://dev.mysql.com/doc/refman/5.1/en/load-data.html。Mysqlimport也值得一看，它是一个命令行工具，基本上是一个装载数据文件的漂亮包装器。