Questions tagged [erd]

Entity Relationship Diagram

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Need feedback on my ER diagram

I want to create a database which allow me to store IT job offers scraped from several various websites. The problem is that job offers from these websites are not described in the same consistent ...
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4answers
9k views

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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1answer
224 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 ...
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1answer
2k 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 ...
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5answers
17k views

Automatically create ER diagram from database schema

I have a database with 193 tables and I need to create an entity-relationship diagram from them. There are no formal relationships between the tables with respect to FKs. The relationships are mapped ...
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1answer
31 views

ERD for yearly budget ceiling advice

I'm working on webdev that involving yearly budget ceiling, but I can't wrap my head around to design such budget ceiling (my first project involving budgeting). So I need some advice. So the scenario ...
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0answers
5 views

Need clarification regarding my EER Diagram

I am currently building an EER diagram for one of my personal projects. It is regarding an e-commerce site that offers physical copies and streams of the movies. One of the requirements for the ...
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1answer
92 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 ...
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0answers
10 views

Weak entity of weak entity

I wonder whether it is possible for a weak entity to have another weak entity dependent on it. Specifically, I have a strong entity QUIZ which comprises of QUESTIONs unique to that QUIZ that I have ...
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1answer
977 views

How to maintain customer addresses for Orders?

The database I am designing is part of a project I am working on. I have come up with 3 simple "business rules": Customers must either be Individuals or Businesses (a business belongs to a certain ...
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1answer
39 views

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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1answer
30 views

Can a foreign key be used for two primary keys?

I'm still a beginner in sql and I have to transform this relation between clients and addresses and vendors and adresses. This uses 2 primary keys(1 for the vendors and 1 for the clients). My question ...
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1answer
201 views

How to create a SELECT statement involving a subtype

Okay, so all I'm trying to do here is "list" the managers who supervised the employee that charged a customer $100 for a rental on November 1st, 1998. My issue is that I don't know how to select the ...
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1answer
49 views

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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1answer
247 views

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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1answer
365 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 ...
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0answers
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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2answers
734 views

How to represent the relationship between artists and albums in an entity-relationship diagram

I'm learning and practicing with the E-R model trying to design a music industry database. With this section of the diagram I have a doubt: I suppose an album can be had by an artist and a band, not ...
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1answer
56 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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0answers
39 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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2answers
464 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 ...
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2answers
222 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
541 views

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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1answer
13k views

Converted ERD into Dependency Diagram 1NF, 3NF

Thats the ERD. I'm studying for an upcoming test and having trouble getting my head around converting this ERD into dependency diagrams. This is from a previous exam that the Lecturer told us to study ...
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1answer
251 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 ...
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0answers
17 views

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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0answers
29 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
232 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 ...
2
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1answer
39 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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0answers
17 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
19 views

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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1answer
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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2answers
36 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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2answers
89 views

How To Add Days And Time For Instructor Schedule [closed]

Problem I need to make a database design (ERD) to display a schedule for every instructor, including the following: day of course (e.g. Saturday or Monday) time it will give course (period from 12 ...
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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 ...
5
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2answers
6k views

How to generate Entity Relationship (ER) Diagram of a on-premises database using Azure Data Studio (macOS)?

I found a similar question for SQL Server Management Studio. But I use latest Azure Data Studio on macOS. We use on-premises SQL Server (not Azure cloud). How can I use Azure Data Studio to generate ...
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2answers
429 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
35 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
48 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
33 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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2answers
77 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
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 ...
0
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2answers
57 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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1answer
537 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
22 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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