Anyone here got experience doing ERD (entity relationship diagrams)

[sports_brah]

I've been tasked with producing an ERD for a something in particular, and have to create a visual diagram of it. Top level eg only the entity types and not the entities as well.

I've got a basic one drawn, but I think that I've missed the thrust of what they are looking for.

Would anyone be prepared just to cast their eye over it and let me know if they think I've done it right/wrong.

Regards

 

[Conscript]

Jesus...I remember doing them about 10 years ago in school. Don't think I actually remember how to do them though, sorry.

(Useless post is useless)

 

[sports_brah]

Jesus...I remember doing them about 10 years ago in school. Don't think I actually remember how to do them though, sorry.

(Useless post is useless)

I already hate them. We're having to do it, before getting into the deep end of actually doing databases.

Cardinality and optionality. My head is already spinning haha.

 

[Begbie]

I done them in college, was a long time ago now mind.

Hated them, probably the last person to ask.

 

[tom_e]

Done them at uni hated them, now work with databases, something went wrong.

 

[shootersam]

Did them a few months ago in school, will try to find my coursework when I get home, but it's probably much more simplified than what they are looking for.

Edit: Although, if it's only top level it might be okay.

 

[sports_brah]

 

[Scougar]

You seem to be missing the actual definition of the relationships. (One to many etc).

 

[Skeeter]

Theres so much wrong with that I don't know where to start...

But assuming both Schools and Admin Office are under Departments, you have 3 main areas; Students, Locations, Departments. Everything else is related to one of those.

 

[sports_brah]

Theres so much wrong with that I don't know where to start...

Thought so. First one I've ever done.

with the bits and bobs on it.

 

[Skeeter]

You don't have to link everything to everything else.

For example, you don't have to link a Student to Modules, Courses, Schools and Departments. A Module will have an associated Course, School, Department, Staff Member, etc, so you can just link the Student with the Module and let the other relationships cascade off of it.

 

[sports_brah]

You don't have to link everything to everything else.

For example, you don't have to link a Student to Modules, Courses, Schools and Departments. A Module will have an associated Course, School, Department, Staff Member, etc, so you can just link the Student with the Module and let the other relationships cascade off of it.

Would you mind if I sent you a list of my entity types and entities that I have derived? (There ERD has more than one question to answer which I haven't posted here yet).

Thanks.

 

[alex20000]

You can't have many to many. I think you have to put a table in between them.

 

[AndrewNR]

You can't have many to many. I think you have to put a table in between them.

Yes, it's known as a relation for a relationship (not just many to many).

You have also missed out the mandatory and optional participation in your diagram.

Edit: naming the relations between the entities will help understand the relationship better, i.e. A student has 0, 1 or more Invoices etc.

 

[sports_brah]

You can't have many to many. I think you have to put a table in between them.

Damn. :/

 

[AndrewNR]

Damn. :/

The 'new entity' will use the other entity's PK(s) as FKs. I don't think you need to worry in a CDM though.

 

[sports_brah]

The 'new entity' will use the other entity's PK(s) as FKs. I don't think you need to worry in a CDM though.

Thanks!

Would you mind me quickly running something past you via trust? (Don't want to post full question up on here )

 

[AndrewNR]

Ok, sure.

 

[fretted]

Where are your lookup items going to be stored?

You should consider using a lookup table to store departments, schools, lecture rooms, modules, etc.

 

[sports_brah]

Ok, sure.

Thanks dude, trust should be with you.