All Questions
159
questions
1
vote
2
answers
74
views
Cardinalities for ternary relations in ERD diagram
Re that ERD:
I can represent a many-to-many relationship with m to m.
What is m to n in the ternary relationship?
Can I use it in a binary or unary relationship?
What does it mean?
What is m to k?
Can ...
- 11
0
votes
0
answers
45
views
How to create an ER diagram: database design challenge
Is this correct or not?
I'm trying to create an ER diagram for an online food delivery app. Now, I'm unsure if the diagram accurately represents the system.
0
votes
1
answer
24
views
How to get the diamond on Siebel erd?
I'm trying to recreate this image, however I can't find the diamond option between the relationships of the entities. How can I do this?
I've tried going through the relationship properties and ...
- 3
1
vote
1
answer
23
views
Depicting different shapes of the same real world entity in an ER Diagram
Given an entity A represented by tableA, that I am going to perform certain transformations on (e.g. pivot, standardise) and store/materialise in a second table tableB should I depict an entity B for ...
- 653
1
vote
2
answers
159
views
How to specify relation based on a condition in Entity Relationship Diagram (ERD)?
Suppose I have a table named User (Entity), whose attributes are _id, name, email, user_type [enum: "normal user", "admin", "volunteer"], address, and age. also, I have ...
- 188
0
votes
1
answer
52
views
UML ERD Database modelling Query [closed]
I have the following tables in my database.
(Member) is assigned to 1.m facility
(Facility) has assigned 1.m member
(Facility) enrolled to 1.m program
(Program) enrolls 1.m facility
I want to query ...
- 3,174
0
votes
1
answer
152
views
In an ERD can 2 actions be connected to each other?
My program allows the user to select up to 3 suburbs in their local region. The website emails the user about road crashes that occurred in those suburbs. It stores their UserID and the suburbs they ...
- 13
2
votes
1
answer
69
views
How to let user change his address without affecting the same one in the order?
I want every order to have one shipping address. But if I added shipping_addresss_id in order table, then if the user ordered something that is shipped and delivered, and after months the user changed ...
- 168
0
votes
1
answer
412
views
How do two many-to-one relationships work inside a ternary ERD diagram?
The arrows represent the many to one relationships.
From my understanding of the diagram:
Suppliers can only relate to one relationship of car and part. For example Tom's warehouse can only sell a ...
- 37
0
votes
0
answers
449
views
Login Entity Relation Diagram: Review and Opinions
I've made a try of an ERD, to model a login system to manage employees, accounts, netkeys, usernames and passwords in an enterprise, but I still think something's missing or could be improved.
So for ...
- 1
-2
votes
1
answer
523
views
Vaccination Database design ERD
My intentions to design the database schema for the small pet vaccination application.
Inside Pet table I want to store details about the pets and if specific vaccination is required.
There are 3-4 ...
- 531
0
votes
1
answer
900
views
What is the best / correct way to deal with null values in a database when you have different types of related data [duplicate]
I've have a structural database design question. I'm curios how I should deal with NULL values and table creation in my database. I've come up with a few solutions myself but I want others to look at ...
- 1,579
0
votes
0
answers
23
views
How to model mutliple Many-To-Many relationships that create a circle
I am looking for direction on how to model something for a database. What I am trying to model is this: I have a list of Services. Each service can be made available to a list of countries. Each ...
- 3,555
0
votes
1
answer
353
views
Chen ERD Relationship Attributes
This is a portion of a Gaming Company Chen diagram that I need to convert to a database. How do I know which entity will get the attributes LastPlayed and CreatedOn? I feel like I could make a case ...
- 37
0
votes
0
answers
1k
views
ERD for an online charity/donation application database
I've been having some trouble setting up the database relationships for a Vue.js/ExpressJS project, I'm looking for some advice on it please.
My ERD at the moment:
My main concern is with the user ...
- 291