Entity Relationship Diagram

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263 views

Entity relationship diagram [closed]

What is the difference between ERD 1 and ERD 2? From what I understand is that ERD 2 has the many to many relationships resolved with a link entity whereas ERD 1 only shows the relationship... is ...
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6answers
23k views

How to export an ER diagram from an Oracle DB?

I am developing this application with an Oracle database. I haven't been documenting the data model, but now an auditor wants to have an entity relationship diagram of my database. There are many ...
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3answers
616 views

how do I model this in database?

I am using mysql as my backend database. Here is the use case; A HolidayPackage is configured with some default offerings. These default offerings can be up/downgraded based on the options provided. ...
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0answers
291 views

Entity relationship modelling, comment on my ERD

Note: Due to low reputation I can't post images so i have added the links accordingly. I have this assignment I'm working and I am stuck in a recursive relationship, following is part of the case ...
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1answer
361 views

Suggest good ERD tool with UML notation

I need to design an ERD with UML notation, can anyone recommend a tool that does this.
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1answer
344 views

ERDs: How do you indicate mutually-exclusive encounters?

If you have a character_instance and character entity in an ERD for a video game, and you want to indicate that something happens when a character entity encounters a character_instance entity, how do ...
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2answers
245 views

Design: How do you decide when items are related vs when they are attributes?

I've been trying to figure this out for a while. Let's say you have a person, for example. An attribute of a person is his or her social security number, right? But a person also has a social ...
3
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1answer
1k views

ERD via Chen's notation: How do I organize multiple 'last done' entries?

I'm having an issue creating a little practice ERD. I'm trying to do some more difficult stuff, and I'm not sure what the standard way to organize it is. Basically, I don't know which of these is ...
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5answers
5k views

Importance of ER Diagrams

I am a student and I am developing several projects as a part of my academia. While developing the database for one of the projects, we came across a situation where we thought about whether ERD is ...
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1answer
683 views

Exporting from SQL Server 2005 for import into ER Studio 9.0

I am new to ER Studio and need to create an ERD for a remote system. That system can only be accessed by LogMeIn remote control and by FTP. The remote system is running SQL Server 2005. The local ...
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1answer
250 views

Query regarding normalization of the relations

I am given a case study of Event Management to develop an ER model and based on it its normalization forms and relational schema. Now i have developed my ER Model based on the SRS that i have ...
2
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2answers
2k views

Is it OK to have an entity in an ER diagram without a relationship?

I'm creating an ER diagram for a class assignment and I was wondering if it would be possible to create an entity that had no direct relationship to any other entity, and simply use foreign keys to ...
3
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1answer
12k views

How can I import the contents of an Oracle database into Visio to create an Entity Relationship Diagram?

I have an Oracle database, and I would like to create an ERD in Visio 2007 Pro. I have so far looked at DBMS_METADATA.GET_DDL commands to generate ddl. I know that I can import an Access DB into ...
7
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2answers
905 views

How to structure a model to properly and efficiently represent tree-like data on relational databases?

Based on Traversing tree-like data in a relational database using SQL question, I would like to know how the way regularly used to describe tree-like data on relational databases considering physical ...
22
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10answers
619 views

What is an effective way of labeling columns in a database?

I used to label columns in my databases like this: user_id user_name user_password_hash To avoid conflicts when joining two tables, but then I learnt some more on how to alias tables, and I stopped ...