Entity Relationship Diagram

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23
votes
10answers
700 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
2answers
468 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 ...
10
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 ...
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
1answer
20k 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
votes
5answers
10k 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
973 views

Modeling a scenario in which each Music Artist is either a Group or a Solo Performer

I have to design an entity-relationship diagram (ERD) for a business context that involves the delineation of music artists, as I will detail bellow. Scenario description An Artist has a Name, and ...
6
votes
2answers
336 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 ...
6
votes
2answers
230 views

Best data modelling approach to handle redundant foreign keys in relational model

I am looking for advice on the best relational modelling approach to store surveys, questions, and responses. I am looking for which of the two approaches below looks best, or an alternative approach ...
6
votes
1answer
1k 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 ...
6
votes
1answer
8k 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 ------------------------- ...
5
votes
2answers
6k 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 ...
5
votes
1answer
62 views

Visualizing Database Schema [closed]

I am not a DBA, but an end user that mashes together data from various databases within my company to generate insights. When I first encounter a new (to me) database, I spend time scrolling ...
5
votes
3answers
2k 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
775 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
445 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 ...
5
votes
1answer
249 views

ERD for a web development company

I am working on an ERD which represents the relationships between entities in a Web development company behavioral model. There I have entities like: Customer Service ----------- (like: web ...
5
votes
2answers
289 views

Dog Adoption Database Design

Apologies if this isn't the norm, but I am seeking advice for the database design for 'dog rescue/adoption'. I've done my normalization research and this is my first attempt at database design. Any ...
4
votes
7answers
46k 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
3answers
98 views

What's the point of the relationship diamond in Entity-Relationship diagrams?

I'm drawing an ER diagram for an ecommerce site that I'm building, and noticed something: the diamond that I am drawing between two models (or entities), which I understand is meant to symbolize the ...
4
votes
1answer
116 views

Modeling Subclass (or Subtype) Constraints in an Entity-Relationship Diagram

Scenario description Can someone help me out on how to model the situation that follows: There is a superclass (or supertype) called PRODUCTS, which has the subclasses (or subtypes) named FOOD and ...
4
votes
1answer
139 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
2k 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
119 views

Entity Relationship Design; The best scenario

TLDR; What would be the best design choice for the scenario below and how would each design react at extremely large data volume? I have experience working with large government database systems ...
3
votes
2answers
941 views

Which one is an ER diagram?

I have started to study ER diagrams. When I browse through the ER diagram tutorials, I found something like figure 1: Figure 1 I tried to create a sample ER Diagram in MySQL Workbench like: ...
3
votes
2answers
140 views

Survey Database - Respondent Table (1NF or 3NF - Pros and Cons)

Building out a Survey ERD ODS layer. Now i'm debating on the design for my Respondent Table. Not sure if its best to have it as 1NF or 3NF. FOr a quick back story I get a survey extract with ...
3
votes
2answers
808 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
2k 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
145 views

How do I read ERD Notation (crow's feet) to convert to Natural Language?

Background I am attempting to insure I understand how to read ERD (Entity Relationship Diagram) notation so I can convert it to a natural language explanation. I'm trying to insure I can explain a ...
3
votes
4answers
130 views

In a one-to-one relationship, where should the foreign key be placed?

I am currently designing an ERD for a project management system. I am unable to choose between two workable solutions as the best solution as I wish to embrace the best standards. The two entities ...
3
votes
1answer
742 views

ER vs database schema diagrams

when i search the web for er diagram and database schema these 3 diagram types found but all are named under er diagram.i want to know what is database schema diagram and what is er diagram why all ...
3
votes
2answers
184 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
2answers
72 views

Is it possible to display this restriction in an ER diagram?

I have a question about modeling a particular kind of restriction, but I don't know the technical term for it, so I will illustrate it with an example. I wish to make an ER diagram for a hotel room ...
3
votes
1answer
1k 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
8k 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 ...
3
votes
1answer
184 views

Entity relationship many to many

Is an association class in UML the same as an Link entity in ERD?
3
votes
1answer
27 views

How to decipher entity relationships in a Physical Data Model given the corresponding Logical Data Model

Can someone use the entity relationships in this Logical Data Model (LDM): to explain the entity relationships in this Physical Data Model (PDM): and how to specify the foreign keys in the PDM?
3
votes
0answers
50 views

ERD for a Contract between a Writer and a Publisher: Is it correct, can it be simpler?

I created an entity-relationship diagram (ERD) for a book publishing business context that I will detail bellow. Entity types The entity types of interest are: Writer Work (as a book) Publisher ...
3
votes
1answer
41 views

Store the content book in database, so that it would be updated afterwards or store them as document?

I have some books in (urdu) made with Urdu Inpage(tool for making pages in urdu) like this: problem that these document files are difficult to read in php because they gives unread-able characters, ...
3
votes
1answer
55 views

How to represent the optionality of a many-to-one mandatory relationship from the Parent to its two Child entity types in an ERD?

I have a Parent entity type with two Child entities, with a relationship cardinality of many-to-one (or M:1) from Parent to Child. The business rules say that: It is mandatory that the Parent ...
2
votes
1answer
64 views

Is this table in my ERD redundant? (Image)

I am developing a research article database for a project. My professor approved this design but I feel like the Author's_University table is redundant and that University_ID could just be added to ...
2
votes
2answers
268 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, cellphones),...
2
votes
1answer
2k 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
220 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
330 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
927 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
1answer
59 views

What is the cardinality of entity relationship between Employee and Department?

Recently, a friend of mine asked me this question about the cardinality between a Department and Employee entities, I replied many to many, then he, my friend, showed me drawings from the internet ...
2
votes
1answer
451 views

Representing a Superclass/Subclass (or Supertype-Subtype) relationship in a MySQL Workbench diagram

Situation I am trying to figure out how to represent a one-to-one (1:1) relationship regarding a superclass/subclass or supertype-subtype structure in an entity-relationship diagram (ERD) of the kind ...
2
votes
2answers
428 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
3answers
7k 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). ...