Questions tagged [erd]
Entity Relationship Diagram
114 questions with no upvoted or accepted answers
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Working on a decision tree database design
I'm doing the conceptual model for a Decision tree database. The goal is store any Decision tree.
I have four entity types: DecisionTree, Node, Branch and Leaf.
Each Decision tree is composed of ...
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5
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1
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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 ...
- 157
4
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0
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311
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Accounting database model
Need to build a service with an internal wallet function.
Here is a simple use-case diagram:
I have made a DB model
But I don't like it for the next reasons
No guarantee there will be only 1 sub-...
4
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2
answers
2k
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Entity-Relationship Diagrams: Identifying which way a relationship flows
I am having trouble grasping the "relationship" concept of an entity-relationship diagram. For example, you have Classroom and Furniture as your entities. If you were to put a relationship diamond ...
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How can I model a medical scenario in an entity-relationship diagram?
I am a self-taught frontend developer that is trying to go full-stack, so I am trying to teach myself data modelling by means of working on some exercises out of a database management book.
In this ...
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3
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1
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Need help with first ER diagram
This is my first time doing the diagram. My teacher isn't the best at helping out or responding to questions so I've come here to ask for further assistance. I think I've mostly got it correct, but ...
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3
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60
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Help Creating a 'Complex' ERD
I am stuck on how to represent the relationships I need correctly. I have a
Produce table. Each type of produce—e.g., 'lettuce'—has one or more quantity suffixes that can be associated with it, e.g., '...
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How to design a database for my entity-relationship diagram about Projects, Tasks and Developers
I'm new to database and my entity-relationship diagram is as follows:
According to that I designed my SQL-DDL database statements as shown below:
CREATE TABLE Developer (
DeveloperID int NOT ...
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3
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Serialized Inventory Tracking
I'm developing a inventory system with optional serial no tracking (which users can turn on for items they select).
in order to keep stock records currently i came up with two options.
Option 01
use ...
- 143
3
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0
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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
Split ...
- 141
2
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0
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73
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One-to-One? or One-to-Zero-or-One?
Scenario: I am being asked to create an HR training tracker for employees of a business. in this database I am using two tables:
EMPLOYEE(EMPLID, LastName, FirstName, PrimaryEmail) with EMPLID as the ...
2
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226
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My relational schema and a few questions about relations and duplicate values in columns
I'm trying to create database in which I could store thousands of job postings. I put here 5 sample records of these job postings so that you could better understand how everything looks like:
Now, ...
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2
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0
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886
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Aggregation Vs Ternary relationship
I am reading a book about database systems and in the chapter covering database design using ER, the author aims to explain when to use aggregation versus ternary relationship. In short, each Project ...
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2
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6k
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Crow's foot notation--what is the difference between "one" and "one-and-only-one" regarding relationship cardinalities?
I'm trying to figure out the difference between the single-bar and double-bar cardinality indicators as in the figure below:
Some sources seem to use one notation while others use the other. I can't ...
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2
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270
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Designing a message system
I want to create a messaging system but I'm stuck in the relationships between the sender/receiver of the message and the message itself.
This is a list of requirements for this system:
Allow both ...
- 191
2
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0
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330
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Modelling a database for a simple IT device tracking scenario
Sorry, my English is not that good.
I need a simple IT device tracking sytem at work.
For each device I need to know its current location, status and ownership (employee to which it is assigned).
...
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2
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678
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Composite attributes in Barker notation
I would like to know how to draw set of entities with composite attribute in Barker's notation. In UML you can do this in that way:
and in Chen's notation:
Please, help. I have final exam day after ...
2
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0
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Modelling a scenario involving architecture firms projects
I'm very new to Database Modelling (using the Finkelstein methodology) and I'm getting confused on a modelling scenario in particular.
I am able to draw out the basics, however am running into some ...
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2
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1
answer
108
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Troubles with an attribute that depends on the value of another attribute
I'm redesigning a health insurance costs database (actually they're not really insurance plans in my country
but I think that for the sake of the example it doensn't matter). We're the health plan ...
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2
votes
1
answer
917
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Drawing an entity-relationship diagram for a store business context
I have an entity called Users, with the attributes Id, Name, and Phone No. The objective is to develop an entity-relationship diagram (ERD for brevity) where Users might be Store Cashiers, and also ...
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2
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782
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How can I draw an entity-relationship diagram for a medical business domain?
I have to develop an entity-relationship diagram (ERD) for a business domain with the following characteristics:
A doctor consults from one clinic only, but a clinic may have many doctors working ...
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2
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0
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1k
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How can I model an ERD with relationships that include "this or that but not both" and "this and that"?
I am having trouble drawing a entity-relationship diagram (ERD) and I wanted to ask for any guidance on what I am doing wrong.
Busines rules
The descriptions of the assignment and of the business ...
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2
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0
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1k
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A Shop can have Products from a Supplier
I'm creating a Platform where Suppliers have Products that Shops can choose, add to their Shop and start selling.
My situation is as follows:
A Supplier can have many Products (for example: 'T-...
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2
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0
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127
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How can you use an entity-relationship diagram to document business processes?
Past exam question: How can you use an entity relationship diagram to document business processes?
As far as I know, I would use an entity-relationship diagram (ERD) to document the relationships ...
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2
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0
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568
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How to resolve "unwanted" recursive relationship?
I'm currently designing a database for concerts, so I have created the following entity-relationship diagram (ERD):
Business domain characteristics
A concert can take place on a regular event or a ...
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2
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0
answers
727
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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?
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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 ...
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2
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0
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1k
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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
So,...
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0
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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 ...
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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 ...
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1
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0
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Table for an Appointment App
experts,
I am building out an appointment scheduler application. I am seeking advice on how best to tackle this issue.
I am building out my ERD and I am the point where I will be creating a ...
1
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0
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926
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Can a foreign key be a primary key?
I want to know the relationship takes, teaches, advisors tables underlined attributes are foreign key or primary key? or both?
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356
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Can I illustrate how a relationship depends on another in an ER diagram?
I'm new to data modelling and trying to build my first ER diagram for supermarket management. My current diagram is based on the following description which I myself come up with:
"Suppliers ...
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1
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0
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224
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Fashion Show ERD
working on a class project.
Have to make a ERD for a fashion show.
Not looking for a super in depth ERD, but one that will give a good grade.
I'd like it to be able to
Have a 'Clock-In/Clock-Out ...
1
vote
0
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99
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Foreign key or copy of attributes in log entities
I am trying to design an ER for a system with the following specifications:
Each user has an account
The user can link his/her bank accounts to his/her account in our system
The user can deposit or ...
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1
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0
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157
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ERD related, can you make one to one relationship with a single attribute entity to another entity?
ERD Here
So for my database project, I designed a meat supply chain optimization project for a large organization, for example such as walmart, where every part of the chain is owned by the ...
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1
vote
1
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378
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ER-Model to relational mapping
"Fundamentals of Database Systems" by Ramez Elmasri covers this topic extensively, I've gone through it and seemingly the rules mentioned aim at converting the ER-Model to a relational ...
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1
vote
2
answers
529
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MySQL - Many to Many relationship, or one to many with additional columns
Our product contains some constraints that made us contemplate which table design will yield the best performance.
Our model:
Question table which contains fields like id, body, difficulty, and tags.
...
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1
vote
1
answer
80
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Determining Cardinality in a Logical Model
How should one determine Cardinality in a Logical Model ?
Should it be based on how the rows of an entity relate to another entity or should we consider the natural relationship between the entities i....
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1
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0
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How to structure SQL data model to maintain data integrity
Background
I'm building a Private Chef booking service where you can book a Chef to cook you a custom Menu. I'm having trouble creating a SQL db schema that accurately represents the domain while ...
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0
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Food Delivery Service Database Design Questions
For a school Food Delivery application I am developing, I’m facing some problems during the ER model design stage. I have to fulfil many requirements but my main issues I’m having are the following:
...
1
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0
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229
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ER Relationship Total and Partial Participation Example
I am trying to understand partial and total participation.
Given the statement:
"Each restaurant must have one or more dishes and each dish must be provided by exact one restaurant."
The below ...
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1
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0
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243
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Cardinality with specialization in enhanced entity-relationship diagrams
I'm currently taking an introduction course to databases and I've come across a problem not described in the textbook.
I'm wondering about the use of cardinality with the use of specialization in ...
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Gaming shop database schema
I'm trying to design schema for my personal project that would be an online gaming shop. I would like to ask you guys for any suggestions/tips on how could I maybe improve my current draft.
Concerns:
...
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1
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0
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705
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Modelling an entity-relationship diagram for a scenario involving companies, services, and clients
I am creating an entity-relationship diagram (ERD) for managing workflow and other details of Company X in which I am maintaining details of the following objects:
Employees of Company X
Services ...
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1
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0
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175
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Creating an entity-relationship diagram about an art fairs and galleries business environment
Scenario description
The charactheristics of the business domain under consideration are:
Each and every art item has a unique identifying number, and also a name and asking price.
Art galleries ...
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1
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0
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446
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How to create entity-relationship diagram for tables that can potentially be united by an "IS A" relationship?
I have this schema:
create table hall(
building-id int,
hall-id int,
capacity int,
primary key(building-id, hall-id)
);
create table semester(
sem-id char(5),
start-date date,
eend-...
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1
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0
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68
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Local Transport Fare design: how to relate departures, destinations and locations
I am doing a conceptual model for local transportation fare app
The goal is for users to quickly check the current fare and the previous fare from one location to the other. Sometimes, the ...
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0
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194
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ERD mostly in text
In LaTeX I can replicate database tables similar to the ones in the diagram below, but I do not want to deal with figuring out how to nicely draw the relation diagrams between the tables. Is there an ...
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Basic ERD analysis for a martial arts business domain
I am working on a basic website in order to support querying results from martial arts tournament data. We use participation data to determine things like who gets to host tournaments, regional awards,...
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