Questions tagged [erd]

Entity Relationship Diagram

Filter by
Sorted by
Tagged with
0
votes
0answers
18 views

Linking Subtype table to another table in EERD

I made this Enhanced Entity relationship diagram for my database project, but there is a problem that I have been mulling over. Over here, it can be seen that MANAGER is under the supertype of ...
-1
votes
0answers
28 views

What do these ERD relationship arrows mean practically? (One to one, zero or one to one)

So let's say we have this situation: I know this means that foreign key fk1 can be assigned to only one primary key id2 and likewise (meaning there cannot be duplicates of fk1 values in table1 as far ...
-3
votes
1answer
30 views

I need to put the data from the diagram in 3NF [closed]

This is a simple list table of a company trying to keep track of employee assignment to company projects (in other words, not a database but a flat one table file). You will design a database for ...
0
votes
1answer
20 views

Survey Database Structure

I am building a database to feed into a PowerBI dashboard. The data is extracted as CSV (SurveyResults) from Survey Monkey which will be loading into the MSSQL database. The outcome i am after is ...
-1
votes
1answer
33 views

Database design for 'pay at table' product (integrating with restaurant APIs)

I am doing a database project for Uni and am trying to figure out how a 'Pay at Table' app would work for restaurants. I Have found this example company that does this https://readytopay.com/ but i ...
3
votes
0answers
33 views

ERD Cinema help [closed]

Im in need of some help. Most of all in the way i think when creating the ERD. I have searched online and asked some people but i think i formulate my question wrong which in turn confuses people. (...
0
votes
1answer
27 views

What does this diamond shape represent in this ER diagram?

And what is testlog in this diagram is it attribute on relationship. Thanks
1
vote
1answer
56 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 ...
1
vote
0answers
49 views

ER Relationship Total and Partial Participation Example

I am trying to understand partial and total participation. Given the statement: "Each restaurant must have one or more dishes and each dish must be provided by exact one restaurant." The below ...
-1
votes
1answer
40 views

ER Diagram Question [duplicate]

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 ...
1
vote
1answer
38 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 ...
0
votes
1answer
120 views

Covering and overlapping constraints

Given that there are 15 entities in E1, 20 entities in E2 and 25 entities in E3, what's the maximum and the minimum number of entities in E0? It's also known that the ISA hierarchy follows the ...
2
votes
0answers
80 views

Aggregation Vs Ternary relationship

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 ...
2
votes
2answers
55 views

How to Represent Equation with Variables in Relational Database

I am building an application to store the different formulas used for different subjects in school, and I have drawn the following database diagram to depict that scenario: I am having trouble ...
2
votes
1answer
43 views

ERD - Multiple FKs with only one of them being filled for each record

I'm designing a database schema for a music platform. Some of the entities as follows: track album band artist A "track" can have an "artist". It can also have a "band" which makes the artist ...
2
votes
1answer
279 views

What do the entity-relationship diagram (ERD) symbols used in DBeaver mean?

I don't understand the ERDs used by DBeaver. The diamonds and dots at the ends of the line arent the crow's foot I'm used to. I've googled the subject and checked the docs but can't find a straight-...
1
vote
1answer
178 views

Hotel Booking Database design problem

I am currently designing (as an assignment for the course at the university) a database for online booking of hotels worldwide and I have stumbled into a problem. Here's is the conceptual design: ...
0
votes
1answer
43 views

Help with an entity-relationship diagram re Manager entity type and its relationships

In the below ER diagram: A manager can have many Users but a User can only have 1 Manager A Manager must be able to assign multiple users to multiple courses Are the manager relationships correct?
1
vote
0answers
267 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 ...
1
vote
0answers
285 views

Crow's foot notation--what is the difference between “one” and “one-and-only-one” regarding relationship cardinalities?

I'm trying to figure out the difference between the single-bar and double-bar cardinality indicators as in the figure below: Some sources seem to use one notation while others use the other. I can't ...
1
vote
1answer
180 views

How to create a correct entity-relationship diagram (ERD) about a video game profits scenario

I'm starting to build my application database, and I'm really new to the this world, so I have a lot of doubts about my ERD and if its entity types and relationships are ok. This is an application ...
0
votes
1answer
25 views

modeling advice for table which may have 2 father tables

I am developing a ERP for a small cooperative with special needs (that'y why they need a non-general solution). I'd like to model the following: A "receipt" can either be incoming or outgoing For ...
1
vote
1answer
179 views

Which table gets the FK? Is there a clear Parent-Child relationship here?

I have the following tables: Each ProductLine will encompass many Parts. For this reason, it initially seemed to me that the Part table is a child of the ProductLine table. However, a part is not ...
0
votes
0answers
144 views

Building an Entity-Relationship Diagram for a Language Dictionary

I need advice on how to build entity-relationship diagram (ERD) for Language Dictionary. Since I did not build ERD before, I will try to explain and show the ultimate goal of this project below. ...
0
votes
0answers
27 views

How to model this scenario in conceptual erd?Bridge entity needed?

I have a house-share entity( primary key : house-share id) and housekeeper entity (primary key: housekeeper id). At any point in time a housekeeper can only work in one house-share. When a ...
2
votes
1answer
39 views

How to model a set of unique objects?

I have an entity type called 'Object', and I need to model an object set as a list of unique objects with variable length. Then, each object could belongs to many object sets. Current entity-...
-1
votes
1answer
76 views

Where to place derived attributes

I have an assignment which requires me to design a database. I have 3 entity types WARD, BED, and BED_ASSIGMENT (which is the "composite" entity type between BED and WARD). The BED primary key ...
1
vote
2answers
179 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 ...
-1
votes
1answer
193 views

ER diagram to Relational Schema (Many to Many relationship)

In this ER diagram, can anyone explain how we should convert the many to many relationships ('view', 'update' and 'diagnose') to Relational Schema and then SQL? What I think is that there shouldn't be ...
1
vote
1answer
109 views

Need help with a table relationships and over-all design

My design is a Netflix clone which has movies and shows just like Netflix. There is also a table called transcodes which will have information on a movie or episode video transcode. My problem is, I ...
0
votes
1answer
50 views

How do I draw the erd to model this scenario?

Customers are billed for the cost for the activity itself and also any "extra" items which are used as part of an activity. So I have the customers entity (identified by customer id) and an item ...
0
votes
0answers
30 views

When do I create a separate entity when drawing conceptual models?

I have these 3 scenarios: Rooms located in a house are assigned a room number within that house - thus, for example, each house has a room number 1. Each room has a phone number etc... My guess is ...
0
votes
0answers
16 views

Convert IS A relationship into relational schema [duplicate]

I'm trying to map below IS A relationship into relational schema. Would there be two tables one for Savings account and one for Checking account each containing their own attributes? Or would there ...
0
votes
1answer
55 views

Creating and querying a database to set hierarchical associations between Groups, Users, Items and Points

I am working with three entity types, Group, User and Item. A Group consists of Users, and a User consists of Items. Now, I have to work with a fourth entity type: Point. I want to be able to ...
0
votes
0answers
208 views

Creating a Database for Multiple Calendars Support

I am trying to create a calendar application that can support multiple calendars, for instance Indian, Nepali, Russian etc. Users can enable or disable the calendars according to their needs. I have ...
2
votes
2answers
1k views

Mapping a 1:1:N ternary relationship to a relational schema

I have a question about mapping (conceptual) n-ary relationships to (logical) relations. Assume we have three strong entity types: Member, Equipment, and Time Slot, and a relationship named Reserves ...
0
votes
0answers
24 views

Database design of user setting

I have users who place Orders. There are some settings that user can decide and that can be applied at User level which means it will be applicable to all future orders that are placed by user or the ...
0
votes
0answers
84 views

Can an entity be an attribute of another entity?

For ER/EER Diagram: I have one entity Stadium and another entity Match. In Match entity I have the stadium as an attribute. The SOCCER database shall keep information about the stadiums used as ...
0
votes
1answer
249 views

EER Diagram - subclasses which are neither disjoint nor fully overlapping

Suppose we are writing an enhanced entity-relationship diagram (EERD) for a company's database. This company offers two services A and B. If the two services were disjoint, then this might look ...
1
vote
1answer
48 views

Setting up a many-to-many relationship based off of two other many-to-many relationships

I have 3 main top level entities: Project (PK: Id) Owner (PK: Id) Product (PK: Id) Here are the rules: A Project can have many Owners. An Owner can have many Projects. A Project can have many ...
1
vote
1answer
31 views

How to specify the domain of an attribute in an entity-relationship diagram (ERD)?

In an ERD (as in, rectangles for entity types, diamonds for relationship types, ovals for attributes, etc.) how would one specify that an attribute is, say, a 5-letter word?
0
votes
0answers
155 views

Syntax to establish a strong and weak entity relationship in MySQL? Weak entity's partial key is different from strong entity's primary key

The following image below depicts an entity-relationship diagram (ERD) of a strong and weak entity. The closest example, I found here (link), required that a foreign key be defined in the weak entity,...
2
votes
1answer
105 views

Does adding a surrogate key get rid of an identifying relationship between two entities?

In the following example, we have a Comments table with a composite primary key (PK) CREATE TABLE Comments ( video_id INT NOT NULL, user_id INT NOT NULL, comment_dt DATETIME NOT NULL, PRIMARY ...
0
votes
2answers
62 views

Modelling two dependent many-to-many relationships

I have a user who may have 0 or more foo's and bar's. Here is a diagram: Each foo has a unique integer ord. If a user has a bar, then this implies that he has a foo with ord=1. A user may not have ...
0
votes
3answers
100 views

Model multiple 1-m relationship to a single entity

I have an entity called Box. This box has a from property which could be from a variety of different entities. It could be from a user, office, import, storage and many more. So far I can think of ...
1
vote
1answer
492 views

Converting (a) an entity-relationship diagram about an airline booking scenario to (b) a relational schema

I am currently following notes on a certain "7 step strategy" to transform an ERD to a relational schema and was wondering some points about step 4, converting one-to-many (1:N) relationships. The ...
1
vote
0answers
60 views

Cardinality with specialization in enhanced entity-relationship diagrams

I'm currently taking an introduction course to databases and I've come across a problem not described in the textbook. I'm wondering about the use of cardinality with the use of specialization in ...
2
votes
1answer
952 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 ...
0
votes
1answer
224 views

Designing a data model for a survey; building the relationships

Let's say I have a survey that will be handed out to many people. I have a hypothetical diagram with User, Question, and Response entities. Should my relationship be one-to-one from question to answer?...
0
votes
1answer
63 views

Entity-Relationship Diagram problem: trying to resolve a tentative many to many relationship

The case study states "each car belongs to a car type" and "each mechanic specializes in a car type or many car types". My current entity type definitions: Car CarType Mechanic My Entity-...