Entity Relationship Diagram

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22
votes
10answers
647 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 ...
10
votes
1answer
2k 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?
8
votes
2answers
1k 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 ...
7
votes
5answers
8k 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 ...
6
votes
3answers
383 views

Help with a scenario of music groups and members in ERD design

Can someone please show me how to construct this ER diagram with the following scenario? I’m confused with the ‘or’ part of it. Description An Artist has a Name, and must be either a Group or a ...
6
votes
2answers
275 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 ...
5
votes
3answers
1k views

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

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.
5
votes
3answers
723 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. ...
5
votes
1answer
16k 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 ...
4
votes
7answers
35k 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 ...
4
votes
2answers
193 views

Conceptual ERD Multi-table many to many, or possibly recursive?

I'm creating a conceptual diagram [yes, I know I've included attributes and keys - but this is just for me to consolidate what I'm doing whilst learning] -- so please treat it as Conceptual with the ...
4
votes
1answer
812 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 ...
4
votes
1answer
38 views

Do I relate entities that are indirectly related when creating a student-course ERD?

I'm trying to create an ERD for a tutor center, this is what I understood from their operations: There is the tutor center director, then under her there are sections/departments. It, math/calculus, ...
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" ...
3
votes
1answer
80 views

How to enforce a constraint over multiple tables?

I have the following five tables: PRODUCT FEATURE PROVIDER PROVIDER_PRODUCT PROVIDER_FEATURE The logic is as follows: A generic PRODUCT can have one or more FEATUREs. There are different ...
3
votes
2answers
545 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'. ...
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 ...
3
votes
2answers
151 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 ...
3
votes
1answer
839 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 ...
3
votes
2answers
5k views

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

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
2answers
4k 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 ...
2
votes
2answers
160 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, ...
2
votes
1answer
1k 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 ...
2
votes
2answers
90 views

How to review Database schema?

I am green been software engineer, my team lead give me a task in PostgreSQL database, I need to determine the relationship of the all 405 tables, but the problem is the database doesn't have any ...
2
votes
3answers
238 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 ...
2
votes
1answer
3k 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 ------------------------- ...
2
votes
3answers
5k 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). ...
2
votes
1answer
234 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, ...
2
votes
1answer
16 views

Should I maintain relationships diagrams in the back-end and the front-end?

I’m developing an Access 2010 database application. It is split into a back-end, holding all the tables, and a front-end, holding all the queries, forms, etc. I find the Relationships tool helps ...
2
votes
1answer
42 views

Database table to keep track of objects

I have a table called FoodMaker and another table called Settings. Every FoodMaker has multiple Settings. I also need a 3rd table to record what has been made, when and with what Settings. It might ...
2
votes
3answers
551 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 ...
2
votes
2answers
219 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 ...
2
votes
1answer
772 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
156 views

Entity relationship many to many

Is an association class in UML the same as an Link entity in ERD?
2
votes
0answers
731 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 ...
1
vote
1answer
2k 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 ...
1
vote
1answer
277 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 ...
1
vote
1answer
261 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 ...
1
vote
2answers
36 views

Trying to design database for eSports Teams - Issue with dependencies

I am trying to design a database in Access for an eSport league (specifically League of Legends North America). I will post what I have and then explain my issue. My issue comes when I try to ...
1
vote
2answers
163 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 ...
1
vote
2answers
311 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 ...
1
vote
2answers
110 views

New to databases - does my ERD reflect good database design?

I'm making a database to hold data for a media player that I'm working on. Originally, I thought to use one table with the fields: {filePath,artist,title,album,track_number,length,date,artworkUrl} ...
1
vote
3answers
437 views

Database design: 4 types of users but have different functionality , separate or one table?

I have 4 types of users: Admins , normal user , company , service provider Admins and normal user share some attributes (id .first name ,last name ,phone ,mail) company and service provider share ...
1
vote
1answer
321 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 ...
1
vote
1answer
481 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 ...
1
vote
1answer
300 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
1answer
861 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
74 views

How to get a surrogate key value in order to put a foreign key in and create relationship?

I am trying to create two relationships between three tables, using foreign keys with values of primary keys, which are surrogate keys. But I don't understand how to enter the right value in the ...
1
vote
1answer
37 views

Financial Inst - Model Role+Relationships b/w Person and Account

A Person can be on one-or-more Accounts. For each Account a Person is on, Person has a certain role on that account i.e. Person 1 is primary on Account 1 Person 1 is joint on Account 2 Person 1 is ...
1
vote
1answer
858 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 ...