Entity Relationship Diagram

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2
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2answers
50 views

Entity Relationship Model - double one to many

ERD A customer submits one or many leads. A lead belongs to one customer. A lead is a request or an inquiry. A lead belongs to one manufacturer. A manufacturer has one or many leads. Tables ...
0
votes
1answer
36 views

Relational Model Design - Entity with one attribute

I am trying to desing a database relational model for an assignment. At first, I design the ER diagram and next the relational model with tables(Schemas). So here's my question : Is it possible for an ...
1
vote
2answers
55 views

Is my ERD valid for airports,cities and airlines database?

My objective is to make a database of airports, cities and the airlines which provide coverage to them. I asked the question before on stackoverflow and the person told me to break up the ...
0
votes
1answer
59 views

Implementing a simple ERD in MySQL: is the implementation below 100% compliant with the ERD?

ERD Consider the following ERD: Tables From it, I derived the following tables: Company ------------------ c_id c_name ------------------ CompanyEmail ------------------ c_id ...
1
vote
1answer
85 views

How much the decision to use ternary or binary relationship influences the accuracy of the model with regards to a given business model?

The question title is very long, so here's a little bit of context to (try to) make it clear. I asked a question regarding ternary relationship. The question was Ternary relationship: what's the ...
2
votes
1answer
125 views

Ternary relationship: what's the difference between having single table and having multiple tables?

Consider the following ternary relationship: Suppose that all entities have only two attributes (PK and Name). Here are the tables I derived (5 tables): Sector ------------------------- ...
0
votes
1answer
101 views

Conversion of simple ERD to Table: is the solution below any good?

Consider the following ERD: Suppose that all entities only have two attributes: a PK plus a name/number. I want to convert that ERD to tables. Is it needed 4 tables (1 for each relationship ...
2
votes
2answers
47 views

Relations between a imeid, sim chip, and account from a cellphone company?

I've never really had a cellphone (that I owned the account to...long story), but at work we have them, and we want to get a series of relations between accounts, devices (mifi's, tablets, ...
0
votes
1answer
54 views

Digital content eCommerce schema advice? [closed]

I don't have much experience designing databases, I'm looking for some advice on my design from more seasoned designers/developers. I'm developing a digital content eCommerce store which will be ...
1
vote
1answer
177 views

Can Anyone please review my database after I did the Normalization ?.Any suggestion is appreciated

User: User_ID,user_name,E-mail Staff: User_ID,Fname,Lname,DOB Student: User_ID fname Lname DOB Lecture: User_ID Admin: User_ID Position ID : P_ID,ROLE_NAME, Staff_position ...
0
votes
3answers
313 views

Db Design of a Room Booking System

I plan on building a web based room booking application for meeting rooms at a company. The requirements are not set in stone and are pretty much left to me, as long as these core ones are met: ...
2
votes
3answers
180 views

Database design for bookmark system

I am creating a bookmark system where people can save their bookmarks. Each user has its own personal page with bookmarks. A bookmark should have atleast one tag and max five. Each user can create ...
0
votes
1answer
136 views

Does my ERD account for my business logic

As part of my new and upcoming project, part of the business logic involves sending each and every one of my customers (assume they number in their 1000s) multiple (possibly customized) emails. Each ...
1
vote
1answer
68 views

Data modelling concepts

Let´s say I have 3 entities. Can I have them all linked to each other "forming a circle" where each one is linked to the other trough a many to many relationship. Cheers
3
votes
2answers
115 views

Can relationships have relationships?

I have the following requirements (as part of a larger system). In the database, I need to maintain a list of parts, suppliers who sell those parts. Many suppliers can sell the same part and each ...
2
votes
2answers
105 views

What do you call a relationship between two entities without a foreign key?

Let's say I have two tables that are related in that one table contains a field that is a key to the other table. In other words, it would be a 1:1 or 1:* depending on constraints. Let's call it an ...
0
votes
1answer
116 views

How to handle versions of an Entity in Database Design

I am working on a new project. The domain logic of the project is as follows: A user uploads a file (Document) and gives a title, then another user comes along and (s)he also tries to upload a file ...
2
votes
0answers
374 views

The nature of the relationship between two tables in MySQL

Good day. I'm designing a database for a research project where we're predicting whether or not young female athletes will rupture their ACL(s) based on the nature of a test jump recorded with a ...
0
votes
1answer
328 views

Which is the redundant relationship in this ER Diagram and why?

Which is the redundant relationship in this ER Diagram and why? A few of my friends and I have been trying to figure it out but keep going in circles. where the attributes of each entity are as ...
1
vote
1answer
109 views

Multi-variance products

My current system houses different variants of Products in different tables; Productgroups Productcolors Productsizes Productmodels Products can reside under 1 Productgroup and can have ...
1
vote
2answers
283 views

Refactoring/normalization - but almost empty table

I normalized a legacy DB into this structure: But I'm not sure if it is correctly normalized. I don't feel very comfortable with the almost empty filters table. The requirements A group contains ...
0
votes
2answers
171 views

ERD Review Please

I am building a simple database driven web application, but from reading so many books on the subject, I know that if my database is messed up, then my application too, will most likely be messed up. ...
2
votes
1answer
480 views

Payment methods conceptual and logical model

I need to create a conceptual and logical (normalized) models of parking house according to the requirements below. It looks to me as a very simple concept that doesn't need all tables to have ...
2
votes
3answers
1k views

Software tool to visualize and print DB diagrams [closed]

I have some SQL Server databases and use SQL Server Management Studio to manage them. However, I find that is not very friendly to create, design and print database diagrams (for existing tables). ...
1
vote
1answer
1k views

How to model entities in an entity relationship diagram?

I'm a beginner Database designer and wondering if anyone can help me understand this. Let's say we want to design a system that has, among other entities, an entity called Vehicle, and another one ...
4
votes
2answers
768 views

Are there any tools to go from ERD to DB design and vice versa?

I'm learning DB design and looking for some tools, preferably open source software, that could help go from an ERD to a DATABASE and vice versa. For the record, the database i'm using is MySQL.
0
votes
1answer
212 views

Users database to store access levels, can I move the non-essential information to another table?

I would like some advice on the best database structure for my system. I have different kinds of users with different access levels, and different information of course. I created a users table with ...
4
votes
1answer
1k views

Modelling Relationships in an E-R Diagram, Table or Foreign Key?

Should a relationship in an E-R diagram be created in the database as a table or a foreign key? For example: a tutor lectures a class I see it as three possibilities: there is a "lectures" ...
4
votes
1answer
435 views

How are indexes represented in an ERD?

What do indexes look like in an Entity Relationship Diagram? I've googled it and I'm unsure what the standard look of an index is in an ERD. And I'm talking about the crowsfoot diagram that includes ...
2
votes
1answer
875 views

How do I persist recurring events?

I've been tasked with designing a system to recur events. Events may recur daily, hourly, monthly or yearly. Users should be able to schedule events "every 3rd Wednesday of the month" or "The 1st of ...
3
votes
2answers
280 views

How do I create a user invitation model?

I am developing an application which allows 'users' to create 'lists'. I have a many-to-many relationship between 'users' and 'lists' (this might not be right). Additionally 'Lists' have many 'Tasks'. ...
9
votes
1answer
878 views

How do you represent VIEWS in an ERD?

Are VIEWS (CREATE VIEW) represented in an ERD? If so, how do you represent them and specify what tables they came from?
3
votes
2answers
3k views

Tool for Reverse Engineering of PostgreSQL Database on Linux (Ubuntu)

Please suggest a tool to reverse engineer a PostgreSQL DB into an entity-relationship-diagram (ERD) or equivalent ?? Ideally, I'm looking for a simple ERD or UML class diagram in a format that is ...
2
votes
1answer
489 views

How to translate high level entity relationship into schema

According to the following articles written by Dr. Chan, we can describe high level entity relationship. (see page-10,11 of doc-A and page9 of doc-B) •doc-A) English Sentence Structure and ...
2
votes
1answer
135 views

Entity relationship many to many

Is an association class in UML the same as an Link entity in ERD?
1
vote
1answer
203 views

Guidance on simplifying the following diagram

I have a case scenario where a customer can book accommodation or flight only or both. I have modeled the accommodation part, however i am making things complex by over-thinking how stuff works in ...
2
votes
1answer
183 views

How can i model this data

A customer can make a reservation for an accommodation, the accommodation can be in a resort or elsewhere. So i would say that a resort can have different types of accommodations, ie. Chalets, ...
1
vote
0answers
238 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 ...
3
votes
6answers
17k 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 ...
5
votes
3answers
569 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. ...
1
vote
0answers
247 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 ...
1
vote
1answer
321 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.
1
vote
1answer
288 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 ...
6
votes
2answers
227 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
votes
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 ...
6
votes
5answers
4k 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 ...
1
vote
1answer
564 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 ...
1
vote
1answer
243 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
votes
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
votes
1answer
10k 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 ...