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ER Modeling

ER Modeling

ER Modeling

I'm trying to document an ER model.  I'm trying to use the correct (crow) symbols and I'm a little confused.  Are you suppose to use the symbols that would show relationships between tables that should occur or only what you plan on inforcing with constraints?

For example:  Say you have a request table and a response table.  Here are the steps writing to the DB.

1) Write request to request table and send XML request to vendor.
2) Wait for the response from vendor and then write response to response table.

Assume in this scenario that its a one to one relationship and each request should have a response.  What should the ERD diagram show?

I have the request table with || to show min 1 and max 1.  I think this is correct.

I have the response table O| to show min 0 and max 1.  I think the max is correct but I don't know if the minimum of 0 is correct.  I set it to 0 for min b/c its not required at the time the request is written.  

Does my question make sense at all?

RE: ER Modeling

I looked at our diagrams and we use a straight line with 11 for 1 and only 1 (no crows feet)-11-.  Crows feet mean many. Then Crows feet with a 0 meaning may have many.  Example May have subjects and subjects may have grades >00<.  Be careful it might blink at you.

I suppose there are other standards possible.

If you do not like my post feel free to point out your opinion or my errors.

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