如何使E-R图与500张桌子？ [英] How to make E-R diagram with 500 tables?

问题描述

在我们公司，我们有一个巨大的项目，有很多桌子。当我的意思很大，大约是500.也许这是正常现象。其中一些表有200多个字段。我发现，试图为整个系统制作一个电子图表会令人困惑，累赘和无用。只要包括这些表就会产生一个可怕的盒子列表。更不用说像spaguetti这样的关系。

你如何记录这些项目？有没有什么技巧来划分和征服项目的结构？

我们使用Microsoft Visio和我们的服务器运行Oracle。

更新：正如所有人都说我们都同意一个500桌面的ERD将是无用的，需要分解。子图中表格分组的方法更有趣。多少桌子太多了？如果我找不到明确的关系路线怎么办？有没有任何可能有帮助的策略或启发式？

解决方案

你需要做两件事：

1. 不要在ERD上放置字段;和


2. 将您的模型分解为对于图表足够小的逻辑分组。

2）真的是重要的。你想限制自己，每个图表最大约20-30个实体（最好少很多）。大多数时候，没有人会关心整个事情。他们可能会关注缔约方如何建模，帐户或系统的其他部分，以及这些关键实体如何与他人相关。

可以（和预期）

真的没有其他方法可以做到。

如果没有不得不是一个ERD，也可以说，一个UML类图，你有一个更大的范围，因为你可以高级实体有效地包含多个表，所以你可以有不同级别的图表。这取决于更重要的是：ERD或对象模型。通常你最终需要两者。

In our company we have a huge project with lots of tables. When I mean a lot it is about 500. Maybe it is something normal. Some of these tables have more than 200 fields. I find that trying to make an E-R Diagram for the whole system will be confusing, tiring and useless. Just including the tables would result in a frightening list of boxes. Not to mention the relations that will flow like spaguetti.

How do you document those projects? Is there any technique for divide and conquer the structure of a project?

By the way we use Microsoft Visio and our servers run Oracle.

Update: As everybody said we all agree that a 500-table ERD will be useless and needs to be broken up in pieces. The method of grouping tables in sub-diagrams is something much more interesting. How many tables are too much? What If I can't find clear routes for the relations? Is there any strategy or heuristic that may help?

解决方案

You need to do two things:

1. Don't put fields on the ERD; and
2. Break up your model into logical groupings that are sufficiently small to diagram.

(2) is really the important one. You want to limit yourself to about 20-30 entities max (and preferably a lot less) per diagram. Most of the time noone will be concerned with the whole thing. They might be concerned with how parties are modelled, or accounts or some other part of the system and how those key entities relate to others.

It's OK (and expected) to repeat entities on different diagrams as appropriate.

There's really no other way to do it.

If it doesn't have to be an ERD and can be, say, a UML class diagram you have a bit more scope because you can high level entities that effectively encompass multiple tables so you can have diagrams at different levels. This depends on what's more important though: the ERD or the object model. Often you'll end up needing both.

这篇关于如何使E-R图与500张桌子？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！