Questions tagged [erd]
Entity Relationship Diagram
321
questions
0
votes
1answer
21 views
Issues Designing ER Diagram
I'm trying to design an ER diagram in the relational database module of my course. We were given a scenario to draw a diagram for and then create a database within Access. I have the database covered, ...
0
votes
1answer
19 views
Domain of Attributes for an Entity?
I am new to DBMS and was reading about the ER Model and entities-attributes. I found the following line in the book which I was reading:
The domain of Composite attributes is the cross product of ...
0
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0answers
12 views
MySQL: create ER diagram, but in text only
With MySQL Workbench it is possible to create a graphical ER diagram; however, this can become very messy when there are many tables and relations, so it might be good to have something like one or ...
1
vote
1answer
93 views
How to represent foreign key in an Extended ER Model in Chen notation?
This is a spin-off of the question at How to represent foreign key in an ER diagram? which is too vague about the needed notation.
There the idea of underlining FKs with a dotted line is stated. I ...
0
votes
0answers
5 views
ERD - [range] : [range] relationship
Could someone tell how to give a description on the following relationship?
One (or each?) Operator is managed by [how many?] Supervisors?
And one (or each?) Supervisor manages [how many?] Operators?
...
2
votes
1answer
20 views
Modelling a relationship which has multiple one-to-many parents
I am attempting to model a relationship which could have two parents, one of them being optional, and the other being mandatory. The design should have the following rules,
A House must exist as the ...
1
vote
1answer
48 views
Chat/conversation history, entity relationship diagram
Totally aware that there are very similar questions, went through each of them, but those are pretty simple/basic solutions from where i took some things and ideas to create below entity relationship ...
0
votes
0answers
25 views
Question about Ternary Entity Relationship Model
I can't wrap my head around these claims concerning this Ternary ER Model.
Unfortunately this is in German so here are the translations:
Prüfer = Examiner
prüft = examines
Fach = Subject
Datum = ...
1
vote
1answer
39 views
Is it possible for total participation constraints to be enforced by an attribute?
For a school Food Delivery application I am developing, I've been told to use the most accurate ER model that captures as many constraints as possible. In particular, I have decided to enforce a given ...
0
votes
1answer
51 views
What is the Relationship between Instagram users and user followers
I'm building a blog project, which each user can follow other users. I'm still figuring out the design and creating the diagrams first. I know that the relationship between users and followers is many ...
0
votes
0answers
20 views
Simple ERD problem
I am a first year in university and just started learning simple concepts about ERD, was just wondering if a foreign key can be given to a table that has a minimum of one, maximum of one cardinality. ...
0
votes
1answer
49 views
Weak Entities + Partial Keys + 2NF [closed]
I'm a bit confused on the concept of weak entities and normalization and couldn't find any answers online. I know that generally weak entities have a partial key to uniquely identify its own records ...
1
vote
0answers
29 views
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 ...
0
votes
0answers
45 views
ISA-to-Table & Primary Key for Relationship Type
1).ER DIAGRAM TO RELATIONAL DATABASE
2).CAN A RELATIONSHIP TYPE HAVE AN ATTRIBUTE WITH A PRIMARY KEY?
Can a relationship type have a primary key (primary attribute), like in the picture below? Can '...
0
votes
0answers
33 views
Use the following business rules to create a Crow’s Foot ERD
Is there any mistake in the ERD???? it looks weird.
0
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0answers
23 views
Strong Relationship Confusion on ER Diagram
In this ER diagram, there's a dashed line between the DAMAGE and RENT entities, signifying a weak relationship. But, as I understand, a weak relationship exists where one entity does not contain a ...
0
votes
1answer
27 views
Can someone give me feedback on my ER diagram?
I am new to creating ER diagrams and was wondering if anyone could review one that I constructed for an assignment. I used min, max notation in my design but I am not entirely sure if I did everything ...
1
vote
0answers
120 views
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:
...
0
votes
0answers
32 views
Need an ERD of the schema mentioned
Need the erd of the schema for doctor, patient and appointment database. scenario is given as under:
Clinic Management Entity-Relationship Model
-Doctor has a unique id, name, address, qualification ...
0
votes
0answers
41 views
What should the language dictionary database contain?
I am new to database modeling and design. I am trying to create a database for my project "Dictionary of Chechen Language". This could be an app where you can find out the translation into English and ...
0
votes
0answers
29 views
Depicting a Unique Constraint on a UML Diagram
I need to show on a diagram a unique constraint involving two attributes. For example, UNIQUE(COLA, COLB).
This is what I have done:
0
votes
1answer
102 views
ER model for barber shop
My team and I are designing a database for a barber shop. The main focus of the project is to allow customers to schedule appointments with barbers for some sort of hair service.
Our problem is that ...
1
vote
1answer
228 views
Alternatives to EAV model
I am looking for a design pattern that would allow me to capture metadata relating to columns on a table. More specifically, here is my situation.
I have a database with fields in a field table, ...
0
votes
0answers
24 views
Basic holiday request database for university
I have been assigned a task to create a database ED diagram with the correct relationships for a annual leave request system which is being used at my workplace. Is this diagram correct? If not could ...
0
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0answers
13 views
Will a weak entity with two relations to two different strong entities use both of their keys?
I have to create an erd with three entities - customer, salesperson, and item. The customer and salesperson are strong entities, but the item is a weak entity. The customer buys the item and the ...
0
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0answers
11 views
Require relation for this business rule
Lots of games are played in each university location every year; but a game between any two universities is played at a given location only one time a year.
Information collected about a game ...
1
vote
1answer
398 views
Does a weak entity always have a weak relationship and total participation in ER diagram?
I've found in some videos that say a weak entity has a total participation and weak relationship in er diagram. In other videos it isn't. I couldn't find a clear explanation for this. Please can ...
0
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0answers
25 views
ER Diagram: A relation is dependent on another relation
Take a look at the ER diagram here: ERD. This is a fragment of the whole ERD. I've included only the part relevant to this question.
This somewhat hypothetical database has 4 entities. Course, ...
0
votes
0answers
90 views
Linking Subtype table to another table in EERD
I made this Enhanced Entity relationship diagram for my database project, but there is a problem that I have been mulling over. Over here, it can be seen that MANAGER is under the supertype of ...
-2
votes
1answer
125 views
I need to put the data from the diagram in 3NF [closed]
This is a simple list table of a company trying to keep track of employee assignment to company projects (in other words, not a database but a flat one table file).
You will design a database for ...
0
votes
1answer
56 views
Survey Database Structure
I am building a database to feed into a PowerBI dashboard.
The data is extracted as CSV (SurveyResults) from Survey Monkey which will be loading into the MSSQL database.
The outcome i am after is the ...
-1
votes
1answer
72 views
Database design for 'pay at table' product (integrating with restaurant APIs)
I am doing a database project for Uni and am trying to figure out how a 'Pay at Table' app would work for restaurants. I Have found this example company that does this https://readytopay.com/ but i ...
3
votes
0answers
142 views
ERD Cinema help [closed]
Im in need of some help. Most of all in the way i think when creating the ERD. I have searched online and asked some people but i think i formulate my question wrong which in turn confuses people. (...
0
votes
1answer
274 views
What does this diamond shape represent in this ER diagram?
And what is testlog in this diagram is it attribute on relationship.
Thanks
1
vote
1answer
158 views
“Diamond Shaped Relationship” What's the formal term?
Consider the following "Diamond-Shaped" entity relationship diagram:
I'm trying to find some formal readings on why this is a bad design - but Googling "Diamond Shaped Table Relationship" only turns ...
1
vote
0answers
83 views
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 ...
-1
votes
1answer
142 views
ER Diagram Question [duplicate]
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 ...
1
vote
1answer
78 views
Understanding many-to-many ternary relationship sets
I am new to entity-relationship diagrams. I'm a bit confused when it comes to interpreting ternary relationship sets such as this:
Does this signify that every relationship instance of Party will ...
0
votes
1answer
473 views
Covering and overlapping constraints
Given that there are 15 entities in E1, 20 entities in E2 and 25 entities in E3, what's the maximum and the minimum number of entities in E0? It's also known that the ISA hierarchy follows the ...
2
votes
0answers
187 views
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 ...
2
votes
2answers
93 views
How to Represent Equation with Variables in Relational Database
I am building an application to store the different formulas used for different subjects in school, and I have drawn the following database diagram to depict that scenario:
I am having trouble ...
2
votes
1answer
47 views
ERD - Multiple FKs with only one of them being filled for each record
I'm designing a database schema for a music platform.
Some of the entities as follows:
track
album
band
artist
A "track" can have an "artist". It can also have a "band" which makes the artist ...
4
votes
2answers
2k views
What do the entity-relationship diagram (ERD) symbols used in DBeaver mean?
I don't understand the ERDs used by DBeaver. The diamonds and dots at the ends of the line arent the crow's foot I'm used to. I've googled the subject and checked the docs but can't find a straight-...
1
vote
1answer
547 views
Hotel Booking Database design problem
I am currently designing (as an assignment for the course at the university) a database for online booking of hotels worldwide and I have stumbled into a problem.
Here's is the conceptual design:
...
0
votes
1answer
60 views
Help with an entity-relationship diagram re Manager entity type and its relationships
In the below ER diagram:
A manager can have many Users but a User can only have 1 Manager
A Manager must be able to assign multiple users to multiple courses
Are the manager relationships correct?
1
vote
0answers
940 views
Aggregation vs Ternary relationship - When to use?
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 ...
1
vote
0answers
1k views
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 ...
1
vote
1answer
731 views
How to create a correct entity-relationship diagram (ERD) about a video game profits scenario
I'm starting to build my application database, and I'm really new to the this world, so I have a lot of doubts about my ERD and if its entity types and relationships are ok.
This is an application ...
0
votes
1answer
25 views
modeling advice for table which may have 2 father tables
I am developing a ERP for a small cooperative with special needs (that'y why they need a non-general solution).
I'd like to model the following:
A "receipt" can either be incoming or outgoing
For ...
2
votes
2answers
581 views
Which table gets the FK? Is there a clear Parent-Child relationship here?
I have the following tables:
Each ProductLine will encompass many Parts. For this reason, it initially seemed to me that the Part table is a child of the ProductLine table. However, a part is not ...
