Questions tagged [erd]

Entity Relationship Diagram

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Is the database design alright? And I'm quite lost with the admin entity here

A quick description of my system would be: there are 2 users: users and admin. User registers on the website. Upon registration, the system will generate a QR code for the user. The user then goes to ...
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5 views

ERD where you can select multiple options/clarification multivalued attributes

This might seem like a stupid question but I want to make sure I get the basics right. Lets say we have a flight with multiple flight options (such a seat selection, meals, extra luggage, etc.) These ...
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31 views

Is my ER Diagram correct according this business rules?

Tiny Hospital keeps information on patients and hospital rooms. The system assigns each patient a patient ID number. In addition, the patient’s last name, first name, date of birth, and date of ...
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If there is mandatory participation between 2 entities in an ERD, does this mean neither of them are strong entities?

Say I have entity A with primary key "key_A" and entity B with primary key "key_B”. I also have that key_A is a foreign key in entity B. My business rules state that every instance of A ...
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18 views

Is My ER Diagram Correct?

I have a task to design database and problem is described as below: I worked the problem and come up with my own design. sorry relations are overlapping I tried to make them explicit as I can My ...
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24 views

ERD for a simple bank system

I tried creating a simple erd for a banking system, I was wondering what can I improve, and where I did wrong. I'll also have to transfer this erd to sql and then try some queries on it. Thanks in ...
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2answers
86 views

Entity Relationship Diagram for Hotel

I tried creating an ERD model for hotel reservation and billing. Are the cardinalities correct, I'm a bit confused about that. And are there any attributes that are not in the right place? If someone ...
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13 views

Meaning of inverted vs non-inverted ISA triangle in EER diagram

I found two different ISA triangles in various books. Like one is inverted triangle(in first figure) and another is non-inverted triangle(as in second figure). Are they give the same meanings? I am ...
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1answer
38 views

Question on EDR: a plant may have one or more harvesting seasons

I working on the following ERD, trying to understand what is the best way to connect the entities in the example of plants! For now I'm just focusing on the right side of the ERD (yellow, orange, ...
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2answers
35 views

I'm trying to create a database for a hotel company with multiple hotels. I'm stuck on how to reserve a room?

I'm using Xampp phpmyadmin for the first time... So I've got the basics of the database. Customers, hotels, rooms etc. The customer can chose a check-in and check-out date. An admin can class a date ...
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1answer
55 views

Where to start learning the IDEF1X method of model notation?

I recently started learning about data modeling. After seeing @MDCCL's diagrams and thoughtful approach here, I'm interested in learning more about IDEF1X. I don't want to pay $200+ for the ISO ...
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1answer
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Are these two ERDs the same? Do they represent the same thing? [Weak entities and multi-valued attributes]

What I want to create is a table in a database for employees in a company. Each employee has a unique identifier ID and a name. Each employee also has a list of skills, the skills are represented as a ...
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55 views

What is the correct way to organize tables for a SQL view?

I'm new to data modeling. Currently working at creating a personal contact manager but I need some help with modeling the table relationships for a given view. The final view columns I'm shooting for ...
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1answer
21 views

How can I categorize entites by their age in an entity relational diagram?

I am designing an entity relational diagram and I need to categorize entities in groups by their age. What I have is an entity of Person and some personal attributes about it. But I want to have ...
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2answers
292 views

How to model weak entity in ER diagram?

I was going through the weak entity concepts and was trying to model the relation Hotel has many rooms. I have come up with the partial solution presented below but i'm having a problem to uniquely ...
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2answers
21 views

multiple entities that share a table

I have this situation where i have two different entities, Researcher and Lab Manager and i want for a both to have a profile. When a user logs in he could be one of the two entities, and searching in ...
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1answer
34 views

What will be the relation between Employees and Players, given that some players are also Employees?

I have a requirement where I need to store information on Employees in a company that owns(?) a sports team and also store information on Players from other teams that are not Employees of this ...
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1answer
27 views

Help needed to design an ER diagram [closed]

I want to design an ER diagram in order to create a database for a small local business. My problem is that the bussiness sells merchandise to persons and businesses both. How can i differentiate ...
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1answer
40 views

Designing User & its Sub User Database Diagram Problem [duplicate]

There are some business category e.g. Travel Agency, Hotel, Car Rental etc. Roles: Management rolesSuper Admin, Staff Customer side roles are Owner, admin and sales counter May be etc. customer side ...
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1answer
30 views

B2B application: users has its own users

B2B Scenario I am trying is that: The following Roles exists in the system: Super Admin Super Admin Staff Owner (client) Admin (owner i.e. client and creates admin to define sales counters) Sales ...
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1answer
21 views

ER Diagram Design

I need Help in making ER diagram that i made a ER diagram of each seperate or making it combine I made it seprate as image attached but how to combine and make it one ER diagram. Module – 1: User ...
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1answer
39 views

Non-product invoice items

I am having difficulty representing additional charges in an invoice. I understand how to represent the association between an invoice and individual items in that invoice with the use of a ...
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2answers
47 views

Anonymous and Public User Table Design in twitter like application

I have schema design problem which I am not 100% sure if my assumptions are correct. So the requirements are: I need to have 2 different type of user, anonymous and public. A user can have both ...
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2answers
173 views

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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1answer
353 views

Is my way of creating a entity relationship diagram correct?

From what I understand, 1)table customer and table order should have a one to many relationship since customer has orders. 2)table order and table payment should have a one to many relationship since ...
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1answer
21 views

How can instructors add users to their classes and at the same time not know all of the institution users?

I have the following entities Institutions - with institutionID and userID Institution Users - with institutionUserID Institution Classes - with institutionUserID, institutionID Institution Class ...
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1answer
32 views

Entity whose possible types differ in the FK

I have one entity called "Groups". "Groups" can be of different types and the difference between each type is the FK. For instance, if a "Group" is of type "Event ...
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2answers
75 views

Financial database model

I am completely new to database modelling (except for some academic knowledge from a long time ago) but for my new project I want to build a database for the following application. I am collecting ...
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1answer
44 views

“Tuples in a weak entity set are partitioned according to their relationship with tuples in a strong entity” - meaning?

http://web.cs.ucla.edu/classes/fall04/cs143/solutions/chap2.pdf In the above link, there is the following statement - "Tuples in a weak entity set are partitioned according to their relationship ...
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1answer
59 views

Weak entity having n instances as the 'one'

I'm struggling with a question, I'm just trying to figure is it even valid , if not where does it violates the rules of a weak entity relationship, I think it's not valid because how can a weak entity ...
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2answers
307 views

One and only one relationship - ER diagram to relational schema

I'm taking this term a DB course as part of my CS studies. This week we began studying the subject of ER diagrams, which I find a bit confusing. I have some uncertainty about the picture above (Note: ...
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1answer
49 views

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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2answers
30 views

Multiple Primary-Foreign Key connections between Tables Redundant?

I have two tables, Reviews and Critic I'm pretty new to RDBMS and I was wondering if the connection between Review.rID and Critic.Review is redundant? My reasoning is that a single critic can have ...
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1answer
47 views

Database scheme design for complex movie system

I'm creating a complex app for cinemas including frontend and reservation system. I struggle with a DB scheme and this is a worst part for me, I was never good in designing DB's. Easily said it's a ...
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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-...
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1answer
41 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, ...
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1answer
33 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 ...
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17 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 ...
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1answer
3k 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 ...
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1answer
25 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 ...
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1answer
2k 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 ...
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1answer
190 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 ...
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1answer
693 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 ...
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1answer
263 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 ...
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35 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 ...
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82 views

Use the following business rules to create a Crow’s Foot ERD

Is there any mistake in the ERD???? it looks weird.
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1answer
76 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 ...
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393 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: ...
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35 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 ...
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1answer
586 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 ...

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