Questions tagged [erd]

Entity Relationship Diagram

Filter by
Sorted by
Tagged with
2
votes
2answers
531 views

How to review Database schema?

I am green been software engineer, my team lead give me a task in PostgreSQL database, I need to determine the relationship of the all 405 tables, but the problem is the database doesn't have any ...
1
vote
2answers
877 views

Trying to design database for eSports Teams - Issue with dependencies

I am trying to design a database in Access for an eSport league (specifically League of Legends North America). I will post what I have and then explain my issue. My issue comes when I try to ...
3
votes
1answer
946 views

What is the best way to represent the relationship between Team and Player in an ERD?

I am working on designing an entity-relationship diagram (ERD) for a football system, I stopped in the relationship between the Player and Team entity types, as we know a player plays for only one ...
2
votes
1answer
2k views

Bicycle Sharing Scheme - ER Diagram

Please compare the directions below to my ER Diagram and tell me if anything is wrong with my ER Diagram Please I think its accurate enough. Oxford City Council is preparing to launch an innovative ...
0
votes
1answer
190 views

Issue with forming correct relationship between subtype and another table in ERD

The focus is on the Cashier table and the Cash Accountability table. The rule is that only Cashiers have Cash Accountability and a Cashier ideally only cashes out once per day. Before I changed the ER ...
0
votes
1answer
561 views

Database Design / ER Diagram

Please take a look at this ER Diagram that I started. I just don't know if I've set it up correctly (I have not made any relationships yet). I just want to know if I have the appropriate "Tables" or ...
0
votes
1answer
1k views

Does my ERD look well designed?

I am making a database at no cost for a local dance school. I'm still very new this would like to be sure that I designed it appropriately. From the front end, the parent will: fill out their ...
1
vote
1answer
527 views

How to get a surrogate key value in order to put a foreign key in and create relationship?

I am trying to create two relationships between three tables, using foreign keys with values of primary keys, which are surrogate keys. But I don't understand how to enter the right value in the ...
0
votes
2answers
1k views

Does an empty entity make any sense in an entity-relationship diagram?

I have an entity that has nothing else than a surrogate key as a primary key. I use it as an element made of a group of other elements For example : TABLE SchoolClass (classNumber INTEGER PRIMARY ...
0
votes
1answer
517 views

Creating an entity-relationship diagram for a recipes business domain

I am doing this simple ASP project for my uni, just wondering if you can guys direct me or give me some advice. The project Idea is to create a recipe website which will allow users to add recipes ...
2
votes
1answer
684 views

Ternary Relationship in an ERD: What would the cardinalities look like in this situation?

There are four entity types in the business domain of relevance: USER, COURSE, MODULE and TOPIC. The business rules go something like this: A Course contains one or more Modules, and each Module ...
0
votes
1answer
2k views

How can I represent a one-to-many relationship with three tables?

I just started using MySQL Workbench drawing an entity-relationship diagram that I previously designed in paper. I want to represent a conceptual one-to-many relationship by means of three tables. ...
0
votes
2answers
169 views

ERD Design for Campground and Campsite

I am designing erd for campground and campsite. In general, a campground has many campsites in it. that lead to one to many relationships. but sometimes campsite has no campground, it appears as the ...
0
votes
1answer
3k views

Is an ER diagram an example of a conceptual, logical or physical schema?

I have been reading databases, and I clearly understand the difference between a conceptual, logical and physical schema. An ER diagram is an example of which of these schema's?
4
votes
1answer
948 views

How to model an “is a” relationship in an ERD using Crow’s foot notation?

I have to create an entity-relationship diagram (ERD) for an assignment. I am doing this in a particular drawing tool with the Crow’s Foot notation. There is however one thing I cannot figure out: ...
0
votes
0answers
48 views

Is the use of my lookup table efficient?

I'm trying to find the best way to architect the relationship in the scenario that: A team can have multiple players, a player may also have multiple teams My first thought was to use a lookup ...
12
votes
3answers
5k views

Modeling a scenario in which each Music Artist is either a Group or a Solo Performer

I have to design an entity-relationship diagram (ERD) for a business context that involves the delineation of music artists, as I will detail below. Scenario description An Artist has a Name, and ...
1
vote
1answer
718 views

How to define User/Permission relationship as M:M?

The Resource relates to Action as M:M via Permission join table/separate entity. User can have many permissions. The same permission may be assigned to multiple users. How to define User-Permission ...
0
votes
1answer
173 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 ...
1
vote
2answers
248 views

New to databases - does my ERD reflect good database design?

I'm making a database to hold data for a media player that I'm working on. Originally, I thought to use one table with the fields: {filePath,artist,title,album,track_number,length,date,artworkUrl} ...
0
votes
1answer
55 views

Relationship issue

I'm working on a ERD with mysql workbench, and i have a little question. I have a Database with this tables: company_address country state city I want to store the address of the company with all ...
0
votes
1answer
3k views

What is the best way to represent an album and song entity in an e-commerce schema?

I'm designing a simple mp3(music) ecommerce site, customers can either buy a single Track or whole Album, an Album is made up of Tracks, so there is a one to many relationship between an Album and a ...
2
votes
1answer
109 views

Database table to keep track of objects

I have a table called FoodMaker and another table called Settings. Every FoodMaker has multiple Settings. I also need a 3rd table to record what has been made, when and with what Settings. It might ...
1
vote
1answer
61 views

Financial Inst - Model Role+Relationships b/w Person and Account

A Person can be on one-or-more Accounts. For each Account a Person is on, Person has a certain role on that account i.e. Person 1 is primary on Account 1 Person 1 is joint on Account 2 Person 1 is ...
3
votes
3answers
2k views

Database design: 4 types of users but have different functionality , separate or one table?

I have 4 types of users: Admins , normal user , company , service provider Admins and normal user share some attributes (id .first name ,last name ,phone ,mail) company and service provider share ...
1
vote
1answer
6k views

Cannot Add Foreign Key Constraint

Can anyone tell me why there are errors such as: Cannot Add Foreign Key Constraint And am I on the right track? My schema looks like this: DDL: DROP DATABASE technology_university_hospital; ...
0
votes
1answer
2k views

ERD Design for Employee Leave

I found the following ERD design: Which trying to capture as much information about employee leave (i.e sick, travel, etc). What am trying to understand is what does the columns: Table : ...
1
vote
2answers
213 views

What would the relational diagram look like in this situation?

Situation Last week I had to do an assignment, and I did not agree with my teacher's ERD. She used a n-ary relationship while I used two binary relationships. I would like to know a true dba's (you) ...
0
votes
1answer
1k views

Cyclic relationships in ER Diagrams

I am trying to draw an generic entity-relationship diagram (ERD) to model a software object (Let's say a XML file). This XML file has references to other XML files. Also, if a XML file (say "file-A") ...
1
vote
1answer
313 views

When to use a multidimensional relationship in an ERD?

When to use a multidimensional relationship in an ERD? My textbook is in Dutch, and the two paragraphs that explain about multidimensional relationships is too vague and brief. I don't understand when ...
2
votes
2answers
1k views

Should I use a three-way associative table?

I have a scenario which I believe I have come up with a solution - however, I can't be sure it's a manageable one, or even correct. The scenario is as follows. There are are three tables involved in ...
1
vote
1answer
172 views

ERDs and modelling ownership of roles within Job table

I'm currently in the process of modelling what I see as a relatively simple relationship through my ERD. I'm not even certain that strictly speaking this is Many-to-Many but nevertheless there are ...
0
votes
3answers
1k views

Completion of ERD, uncertainties about generalization/specialization and primary keys

I'm practicing making conceptual databases and I would like to know of I'm on the right track. I've been trying to create an ERD for a scenario as follows: A hotel can take bookings for weddings, ...
0
votes
0answers
26 views

How to model mappings at various levels

I'm trying to design the database model for my application and I'm finding it difficult to design the mappings for user access to various entities stored in the database. If access was only ...
0
votes
1answer
10k 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 thes ERDs into dependency diagrams. This is from a previous exam that the Lecturer told us to ...
2
votes
3answers
816 views

Entity Relationship Model - double one to many

ERD A customer submits one or many leads. A lead belongs to one customer. A lead is a request or an inquiry. A lead belongs to one manufacturer. A manufacturer has one or many leads. Tables ...
2
votes
2answers
128 views

Composite primary key plus a separate (surrogate) id column for foreign key references

I am trying to build a database about locations like so: Country → Region → Town Countries will be populated with a list of pre-defined worldwide countries, regions & towns are input by users. ...
2
votes
2answers
3k views

Relational Model Design - Entity with one attribute

I am trying to design a database relational model for an assignment. First, I design the ER diagram, and then the relational model with tables (schemas). Here's my question: Is it possible for an ...
2
votes
2answers
477 views

Is my ERD valid for airports,cities and airlines database?

My objective is to make a database of airports, cities and the airlines which provide coverage to them. I asked the question before on stackoverflow and the person told me to break up the many-to-...
1
vote
1answer
196 views

Implementing a simple ERD in MySQL: is the implementation below 100% compliant with the ERD?

ERD Consider the following ERD: Tables From it, I derived the following tables: Company ------------------ c_id c_name ------------------ CompanyEmail ------------------ c_id e_id --...
1
vote
1answer
3k views

How much the decision to use ternary or binary relationship influences the accuracy of the model with regards to a given business model?

The question title is very long, so here's a little bit of context to (try to) make it clear. I asked a question regarding ternary relationship. The question was Ternary relationship: what's the ...
8
votes
1answer
19k views

Ternary relationship: what's the difference between having single table and having multiple tables?

Consider the following ternary relationship: Suppose that all entities have only two attributes (PK and Name). Here are the tables I derived (5 tables): Sector ------------------------- ID_Sector ...
2
votes
1answer
688 views

Conversion of simple ERD to Table: is the solution below any good?

Consider the following ERD: Suppose that all entities only have two attributes: a PK plus a name/number. I want to convert that ERD to tables. Is it needed 4 tables (1 for each relationship plus ...
2
votes
2answers
503 views

Relations between a imeid, sim chip, and account from a cellphone company?

I've never really had a cellphone (that I owned the account to...long story), but at work we have them, and we want to get a series of relations between accounts, devices (mifi's, tablets, cellphones),...
2
votes
2answers
935 views

What are the bad design points in the following (simple) Entity-Relationship Diagram?

The objective is to design an Entity-Relationship Diagram for a company that has addresses, telephones, emails and representants. Here's the list of the constraints: a company has one or more ...
2
votes
1answer
158 views

Database Design Techniques, Notations and Terminology

I'm taking a Database course and I'm a bit confused with the different types of graphical representations terminology of a database design. Are Data Model, Crows Foot Notation, Crows Foot Model, ERD &...
0
votes
1answer
4k views

Digital content eCommerce schema advice? [closed]

I don't have much experience designing databases, I'm looking for some advice on my design from more seasoned designers/developers. I'm developing a digital content eCommerce store which will be ...
1
vote
1answer
495 views

Can Anyone please review my database after I did the Normalization ?.Any suggestion is appreciated

User: User_ID,user_name,E-mail Staff: User_ID,Fname,Lname,DOB Student: User_ID fname Lname DOB Lecture: User_ID Admin: User_ID Position ID : P_ID,ROLE_NAME, Staff_position :Staff_position_ID,P_ID,...
1
vote
3answers
6k views

Db Design of a Room Booking System

I plan on building a web based room booking application for meeting rooms at a company. The requirements are not set in stone and are pretty much left to me, as long as these core ones are met: Users ...
3
votes
3answers
3k views

Database design for bookmark system

I am creating a bookmark system where people can save their bookmarks. Each user has its own personal page with bookmarks. A bookmark should have atleast one tag and max five. Each user can create ...