Questions tagged [erd]

Entity Relationship Diagram

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1answer
811 views

Ternary Relationship or (n-ary)

I'm trying to find the difference in terms of modeling a ternary relationship v/s a binary relationship in the following case. Any piece of advise would help me a lot. Company has editors who are ...
2
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1answer
1k 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
104 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?
2
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1answer
686 views

Can an entity in an entity-relationship diagram have more than one relationship?

I am practicing drawing entity-relationsip diagrams and in the example it states "many employees work on a project, and employee can work many projects but can only be assigned to at most one project ...
2
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0answers
527 views

What is the difference between (Superclass/Subclass) Total and Partial Specialization?

What is the difference between total and partial specialization of superclass/subclass (or supertype-subtype) structures in enhanced entity-relationship modeling?
3
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0answers
797 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 ...
4
votes
3answers
5k 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: Figure ...
1
vote
1answer
72 views

How can I better model the relationships in this project?

I'm developing an internal tool (as an intern). We deal with a lot of hardware, which is all custom and managers have a hard time knowing who is developing on what machine. The three main things to ...
3
votes
1answer
932 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 ...
1
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0answers
105 views

Ternary relationship with history tracking

I have the following entities Procedure -> id_procedure , desc_procedure . Status -> id_status , desc_status . Subprocess -> id_subprocess , desc_process . The rules are: 1 procedure ...
1
vote
1answer
3k views

relation between customer and product with review

I draw this ERD but I'm not sure if the relation in customer and product with review is correct. also, is it right that I made Rate, Date and time this way ? this is my Description for review Each ...
2
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0answers
108 views

ERD to SQL Server

I am working on an assignment and am having one heck of a time getting my head wrapped around these questions. I need to be able to write in SQL Server 2014 certain select statements based solely off ...
2
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0answers
482 views

Handling Strong and Weak entity types in a one-to-one relationship

I am modelling a database for a term project and I have come across something I do not have a definite answer to. Diagram I was supplied with the following Entity-Relationship diagram: Description ...
0
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1answer
254 views

Should a TeamMembers table have a relationship with the Student Table or the Enrolment Table?

I'll keep it nice and short and simply link to the ERD: Users can be assigned a role, one of those is student. So for the sake of this, Students are the same as Users! A Student can be enrolled in ...
6
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1answer
3k 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 ...
0
votes
1answer
59 views

Normalizing data for joins, dedicated columns, a view or.. something else? [closed]

As an example, i have the following tables USERS, USER_JOBS and USER_HOUSES USER_JOBS keeps a list of jobs for a given user_id USER_HOUSES keeps a list of houses for a given user_id the common use ...
0
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2answers
531 views

Modeling a product database and dealing with inheritance

So, to get better at designing databases, I'm attempting to model a database system after the AR15 Builder. Here is what I have so far: While it makes sense logically, I'm afraid there may be ...
2
votes
1answer
52 views

Can someone please tell me where I went wrong for an exercise submission?

I recently submitted an assignment in a group for our databases class and we lost points on one of the exercises and the correction is unclear. If someone could examine the question, the submission ...
4
votes
3answers
2k 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 ...
5
votes
3answers
6k 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 ...
5
votes
4answers
9k 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 ...
2
votes
2answers
387 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 ...
2
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2answers
1k 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 ...
0
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0answers
92 views

Difference between has and contains in ERD diagram [duplicate]

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
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1answer
2k 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 ...
1
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0answers
146 views

ERD Diagram based on Crow's Foot model for Milky Way Jewelry

this was on my final exam this past winter exam season, in search for the answer since i got it wrong: Draw an ERD diagram based on the Crow's Foot model for a database to support the basic ...
17
votes
2answers
10k views

Implementation of a many-to-many relationship with total participation constraints in SQL

How should I implement in SQL the scenario depicted in the following Entity-Relationship diagram? As it is shown, every A entity type occurrence must be related to at least one B counterpart (...
4
votes
1answer
675 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 ...
2
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0answers
1k views

What is a good database design approach for my Online Quiz Android Application?

I have been working on an Android Online Quiz Application with PHP & MySQL. I know what attributes i need however when designing the relationship it becomes complex and confusing when I analysed ...
5
votes
1answer
1k views

Is my entity-relationship diagram about customers and accounts correct?

Business domain description Each customer has a name, a permanent address, and a social security number. Each customer can have multiple phone numbers, and the same phone number may be shared by ...
2
votes
1answer
222 views

ERD to Relational schema

I'm new to DBM and I'm trying to learn it online. Honestly, I need some help with this. I don't know if I'm doing this right, and any help will be appreciated. This is my answer for i.
5
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1answer
874 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 ...
5
votes
2answers
2k 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 ...
1
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1answer
1k views

ERD modeling organization and roles

I am trying to model the following scenario: -I have multiple company bureaus. -Each Bureau has multiple offices -Each office has multiple divisions -Each Bureau has employees that only ...
2
votes
2answers
8k views

What does the Union sign in EER diagrams mean?

I know disjoint and overlapping, but what does the union like sign mean in an enhanced entity-relationship (EER) diagram...? For example: In other words, what does this diagram mean?
0
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2answers
74 views

What is the most efficient way to make a Locality Entity (Town, City, Village etc) with a Country Entity?

I am new to Database. I have a database with a UserProfile Entity. I need to add a Country and Locality(City, Town, Village) to the UserProfile. What is the most efficient way of doing so? This is ...
2
votes
1answer
150 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 ...
11
votes
2answers
1k views

Best data modelling approach to handle redundant foreign keys in a database about Surveys, Questions and Responses

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 ...
2
votes
1answer
6k 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 ...
3
votes
1answer
11k 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 ...
0
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1answer
1k views
1
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1answer
157 views

ESports League ERD

I'm creating a database for an esports league and am having some issues putting it all together for an ERD. Here's a quick rundown on how the game works: There are 2 teams of 5 Players each. These ...
1
vote
1answer
586 views

Help me to create correct ER Diagram [closed]

I want to create a database where one user can either be a Doctor or a Patient (but not both). So that, I can get all doctors or patients from doctor or patient table as well as I can search doctor or ...
1
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0answers
1k views

Quotation and invoice mysql table

I am trying to develop a small business web application for my friends business. I do have some php,html experience so I have done the interface and all. Now I am trying to work on the database. The ...
2
votes
1answer
760 views

One-to-many relationship on a “‘junction’ table”

I have two entity's - Workout and Exercise. These will have a 'many-to-many' (M:N) relationship through the junction table WorkoutExercise. Things start to get complicated when I need to have a 'one-...
7
votes
3answers
6k views

Need help on my first ER diagram

I just started my first Database course online, and I have a homework assignment to create an entity-relationship diagram (ERD) from a list of specifications. The specs are as follows: The company ...
2
votes
1answer
333 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 ...
5
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1answer
2k 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 ...
4
votes
1answer
463 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, ...
1
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2answers
1k views

How to decide when is use ERD or UML for data modeling?

A UML diagram can be used both to model database designs and class designs, but an ER diagram should be used exclusively in database problems. How do you pick one graphical representation over the ...