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Go Back  dBforums > General > Database Concepts & Design > List business rules from ER diagram??

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Old 04-15-10, 06:24
cookpau01 cookpau01 is offline
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List business rules from ER diagram??
I need to come up with a list of 12 business rules that can be deduced from the following ER Diagram. I am finding it hard, can anyone come up with any?

Thanks,

Convention:

Dotted Line = Optional
Dotted and Solid Line = Weak
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Last edited by cookpau01; 04-15-10 at 06:54.
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Old 04-15-10, 06:26
pootle flump pootle flump is offline
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Based on what you have learned so far, what can you tell us about that diagram?
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Old 04-15-10, 06:30
cookpau01 cookpau01 is offline
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Well I can tell you that there is a one to many relationship between degree program and Student which is a weak entity.
There is then a many to many relationship between student and module which is an optional entity.

So the business rule I have so far are:
A student does not have to have a module
Students can attend many modules
Modules are made up of many students
A student can only be on one degree course
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Old 04-15-10, 06:38
pootle flump pootle flump is offline
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Looks like a good start.
What makes you say this?
Quote:
Originally Posted by cookpau01 View Post
Student which is a weak entity.
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Old 04-15-10, 06:41
cookpau01 cookpau01 is offline
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Because I am sure that the notation in the diagram of a mix of solid and dashed line means that it is a weak entity. Meaning that the entities very existence depends on another entity.
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Old 04-15-10, 06:43
cookpau01 cookpau01 is offline
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Well thats the convention that we have been using anyway
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Old 04-15-10, 06:51
pootle flump pootle flump is offline
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Ok - that is fine then. I would mention that is not the recognised definition of a weak entity.

I think your business rules are fine so far. I am no lecturer or student so again you will have to fit this in to your definitions however to my mind you have defined the "complex" business rules first. I think you can decompose them in to several simpler business rules which your more complex rules will build on. Whaddaya think?
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Old 04-15-10, 06:53
cookpau01 cookpau01 is offline
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I agree, I think that is the bit that I am finding difficult to do.
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Old 04-15-10, 06:55
pootle flump pootle flump is offline
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Ignore the lines\ relationships. Whaddaya see?
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Old 04-15-10, 06:56
cookpau01 cookpau01 is offline
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Student
Degree
Module
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Old 04-15-10, 06:59
cookpau01 cookpau01 is offline
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So I suppose you could say:
There is a selection of module
There is a selection of degree programs
There are many students

???????
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Old 04-15-10, 07:01
pootle flump pootle flump is offline
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Quote:
Originally Posted by cookpau01 View Post
Student
Degree
Module
I think these are the fundamental business units of the organisation you are modelling. Would you agree?
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Old 04-15-10, 07:23
cookpau01 cookpau01 is offline
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Yes they are
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Old 04-15-10, 07:33
pootle flump pootle flump is offline
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Ok - wanna restate your rules so far?
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Old 04-15-10, 07:35
cookpau01 cookpau01 is offline
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A student does not have to have modules
Students can attend many modules
Modules are made up of many students
A student can only be on one degree program
There are a selection of modules
There are many students
There are many degree programs
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