Entity Relationship Diagram

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6
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3answers
863 views

Help with a scenario of music groups and members in ERD design

Can someone please show me how to construct this ER diagram with the following scenario? I’m confused with the ‘or’ part of it. Description An Artist has a Name, and must be either a Group or a ...
0
votes
2answers
1k views

Which is the redundant relationship in this ER Diagram and why?

Which is the redundant relationship in this ER Diagram and why? A few of my friends and I have been trying to figure it out but keep going in circles. where the attributes of each entity are as ...
3
votes
2answers
507 views

Which one is an ER diagram?

I have started to study ER diagrams. When I browse through the ER diagram tutorials, I found something like figure 1: Figure 1 I tried to create a sample ER Diagram in MySQL Workbench like: ...
1
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2answers
3k 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 ...
0
votes
0answers
16 views

Software to manage ERD [closed]

We have a small database (Around 50 tables) under development, and I am being asked to produce an ERD for the development team when ever a change is made. Using Management Studio is tricky, because we ...
2
votes
1answer
224 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: ...
3
votes
0answers
45 views

ERD for a Contract between a Writer and a Publisher: Is it correct, can it be simpler?

I created an entity-relationship diagram (ERD) for a book publishing business context that I will detail bellow. Entity types The entity types of interest are: Writer Work (as a book) Publisher ...
4
votes
2answers
196 views

Best data modelling approach to handle redundant foreign keys in relational model

I am looking for advice on the best relational modelling approach to store surveys, questions, and responses. I am looking for which of the two approaches below looks best, or an alternative approach ...
0
votes
1answer
112 views

Database Design / ER Diagram - Help Needed

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 ...
1
vote
1answer
51 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 ...
1
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0answers
42 views

Ternary relationship with history tracking

I have the following entities Procedure -> id_procedure , desc_procedure . Status -> id_status , desc_status . Subprocess -> id_subprocess , desc_process . The rules are: 1 ...
3
votes
1answer
36 views

Store the content book in database, so that it would be updated afterwards or store them as document?

I have some books in (urdu) made with Urdu Inpage(tool for making pages in urdu) like this: problem that these document files are difficult to read in php because they gives unread-able characters, ...
3
votes
1answer
37 views

How to represent the optionality of a many-to-one mandatory relationship from the Parent to its two Child entity types in an ERD?

I have a Parent entity type with two Child entities, with a relationship cardinality of many-to-one (or M:1) from Parent to Child. The business rules say that: It is mandatory that the Parent ...
1
vote
1answer
43 views

relation between customer and product with review

I draw this ERD but I'm not sure if the relation in customer and product with review is correct. also, is it right that I made Rate, Date and time this way ? this is my Description for review Each ...
2
votes
0answers
40 views

ERD to SQL Server

I am working on an assignment and am having one heck of a time getting my head wrapped around these questions. I need to be able to write in SQL Server 2014 certain select statements based solely off ...
1
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0answers
37 views

Handling Strong and Weak entity types in a one-to-one relationship

I am modelling a database for a term project and I have come across something I do not have a definite answer to. Diagram I was supplied with the following Entity-Relationship diagram: ...
0
votes
1answer
45 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 ...
0
votes
0answers
20 views

What is the correct database design for accommodating a request and a receive transactions?

In my project management system, I have a feature that requests a rental from a supplier. Once the set of equipment arrives, I can now create a rental receive to monitor the equipment inventory which ...
0
votes
0answers
9 views

Database ERD for orders info

I have two tables: 1-orders order_id 2-shipping_and_billing order_id FK address_type(billing and shipping ) city I need to get full info of shipping and billing in single select of ...
0
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0answers
13 views

Entity–relationship model and relational model

Entity–relationship model is conceptual model... it defines the conceptual view of a database. It works around real-world entities and the associations among them it is implemented in a ...
4
votes
1answer
57 views

Visualizing Database Schema [closed]

I am not a DBA, but an end user that mashes together data from various databases within my company to generate insights. When I first encounter a new (to me) database, I spend time scrolling ...
4
votes
3answers
82 views

What's the point of the relationship diamond in Entity-Relationship diagrams?

I'm drawing an ER diagram for an ecommerce site that I'm building, and noticed something: the diamond that I am drawing between two models (or entities), which I understand is meant to symbolize the ...
1
vote
1answer
176 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 ...
1
vote
1answer
52 views

Normalizing data for joins, dedicated columns, a view or.. something else? [closed]

As an example, i have the following tables USERS, USER_JOBS and USER_HOUSES USER_JOBS keeps a list of jobs for a given user_id USER_HOUSES keeps a list of houses for a given user_id the common use ...
0
votes
2answers
43 views

Modeling a product database and dealing with inheritance

So, to get better at designing databases, I'm attempting to model a database system after the AR15 Builder. Here is what I have so far: While it makes sense logically, I'm afraid there may be ...
3
votes
2answers
105 views

How do I read ERD Notation (crow's feet) to convert to Natural Language?

Background I am attempting to insure I understand how to read ERD (Entity Relationship Diagram) notation so I can convert it to a natural language explanation. I'm trying to insure I can explain a ...
5
votes
1answer
215 views

ERD for a web development company

I am working on an ERD which represents the relationships between entities in a Web development company behavioral model. There I have entities like: Customer Service ----------- (like: web ...
0
votes
0answers
14 views

Difference between has and contains in ERD diagram [duplicate]

I am working on an ERD which represents the relationships between entities in a Web development company behavioral model. There I have entities like: Customer Service ----------- (like: web ...
6
votes
1answer
8k 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 ------------------------- ...
0
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0answers
37 views

Are my two proposed solutions on modelling resources inventory decent?

In the project management system that I am developing, I am wondering what is the best database design for keeping track of the resources inventory. While I want to determine what resources are ...
3
votes
4answers
116 views

In a one-to-one relationship, where should the foreign key be placed?

I am currently designing an ERD for a project management system. I am unable to choose between two workable solutions as the best solution as I wish to embrace the best standards. The two entities ...
3
votes
2answers
131 views

Survey Database - Respondent Table (1NF or 3NF - Pros and Cons)

Building out a Survey ERD ODS layer. Now i'm debating on the design for my Respondent Table. Not sure if its best to have it as 1NF or 3NF. FOr a quick back story I get a survey extract with ...
3
votes
2answers
66 views

Is it possible to display this restriction in an ER diagram?

I have a question about modeling a particular kind of restriction, but I don't know the technical term for it, so I will illustrate it with an example. I wish to make an ER diagram for a hotel room ...
1
vote
0answers
64 views

ERD Diagram based on Crow's Foot model for Milky Way Jewelry

this was on my final exam this past winter exam season, in search for the answer since i got it wrong: Draw an ERD diagram based on the Crow's Foot model for a database to support the basic ...
1
vote
0answers
130 views

What is a good database design approach for my Online Quiz Android Application?

I have been working on an Android Online Quiz Application with PHP & MySQL. I know what attributes i need however when designing the relationship it becomes complex and confusing when I analysed ...
0
votes
0answers
14 views

ERD question, problem with connecting

So I have a question involving an assignment i got. The question is I can see out of a query the total amount of days a room was occupied. However I think my Reservations and Rooms should be many to ...
1
vote
1answer
53 views

ERD to Relational schema

I'm new to DBM and I'm trying to learn it online. Honestly, I need some help with this. I don't know if I'm doing this right, and any help will be appreciated. This is my answer for i.
3
votes
1answer
555 views

ER vs database schema diagrams

when i search the web for er diagram and database schema these 3 diagram types found but all are named under er diagram.i want to know what is database schema diagram and what is er diagram why all ...
3
votes
1answer
97 views

Entity Relationship Design; The best scenario

TLDR; What would be the best design choice for the scenario below and how would each design react at extremely large data volume? I have experience working with large government database systems ...
5
votes
2answers
256 views

Dog Adoption Database Design

Apologies if this isn't the norm, but I am seeking advice for the database design for 'dog rescue/adoption'. I've done my normalization research and this is my first attempt at database design. Any ...
1
vote
1answer
58 views

ERD modeling organization and roles

I am trying to model the following scenario: -I have multiple company bureaus. -Each Bureau has multiple offices -Each office has multiple divisions -Each Bureau has employees that only ...
0
votes
2answers
48 views

What is the most efficient way to make a Locality Entity (Town, City, Village etc) with a Country Entity?

I am new to Database. I have a database with a UserProfile Entity. I need to add a Country and Locality(City, Town, Village) to the UserProfile. What is the most efficient way of doing so? This is ...
2
votes
1answer
64 views

Is this table in my ERD redundant? (Image)

I am developing a research article database for a project. My professor approved this design but I feel like the Author's_University table is redundant and that University_ID could just be added to ...
1
vote
1answer
99 views

How to add foreign key with more than 1 field in SQL Power Architect

In the picture, I got a model I'm building in SQL Power Architect. I already have table 1 referencing a field (CDCONTR) from table 2. But I want to make the foreign key to reference two fields from ...
0
votes
1answer
352 views

Superclass/Subclass Relationship Implementation in MySQL Workbench ERD Diagram

This is a relational model! Trying to figure out how to implement a 1:1 superclass/subclass relationship in the ERD diagram. I'm new to this so I'm not sure whether I have to type out all the ...
2
votes
1answer
301 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 ...
1
vote
1answer
44 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 ...
1
vote
1answer
93 views

Help me to create correct ER Diagram [closed]

I want to create a database where one user can either be a Doctor or a Patient (but not both). So that, I can get all doctors or patients from doctor or patient table as well as I can search doctor or ...
1
vote
0answers
264 views

Quotation and invoice mysql table

I am trying to develop a small business web application for my friends business. I do have some php,html experience so I have done the interface and all. Now I am trying to work on the database. The ...