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Questions tagged [erd]

Entity Relationship Diagram

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ER model of an online bookstore

By my study, I am required to create an ER model. This is the first time I have done this, and I am not sure if the connections are correct. Can you please tell me if they look correct? Thank you in ...
Andrenov Ruslan's user avatar
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1 answer
37 views

Recommended way to build database to contain users and chatgpt data

I am looking to create a Rails application to interface between users and Azure ChatGPT. I will include my ERD diagram showing a couple of options in building the database tables and table ...
Chris's user avatar
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How to implement historical data with this EERD?

I am looking for a way to implement historical data with the following EERD (what I have tried, below the image): What have I tried? Temporal tables Didn't work because I use MySQL and it has no ...
user23600793's user avatar
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Associative relationship for "manager working term"

I am creating ERD following some database design requirements. This specific part on the ERD is what I am trying to represent. I made the MANAGEMENT entity because it's related to DATE_ACCEPTANCE, ...
Albert's user avatar
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1 answer
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Should I Use a Composite Key or a Single-Column Primary Key in my Entity Relationship Diagram?

I am designing an Entity Relationship Diagram (ERD) for a database that includes a table with variants annotated by different tools. In this table, each variant is annotated by a specific tool, and ...
Cristian Riccio's user avatar
-1 votes
3 answers
109 views

2nd Normal Form ERD thoughts

This ERD has completed 2nd Normal Form normalisation, as every table has a primary key, the data is atomic, there are no repeated groups, and there is no partial key dependency. What are your thoughts?...
McNanners's user avatar
1 vote
1 answer
93 views

pgAdmin 4 ... is not present in the table

Hello Here is my erd and the below my creating table codes; -- This script was generated by the ERD tool in pgAdmin 4. -- Please log an issue at https://redmine.postgresql.org/projects/pgadmin4/...
bershinn's user avatar
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feedback and improvements for London Autos ERD

London Autos has several locations within London and its surroundings, from its humble beginning a decade ago in an east London garage, the business has expanded into a multi-million-pound business. ...
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is this ERD(Entity Relation Diagram) is correct or not?

I am creating an ERD for my college project. can anyone tell me if my ERD is correct or not. if not then what are my mistakes. I am creating this ERD from django app. I generated the UML diagram with ...
gurpreet singh's user avatar
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2 answers
38 views

in ERD of a system in which teachers evaluating other teachers of their departments how can i connect Teacher, evaluation_result entiy,

A teacher could be an evaluator and also be an evaluatee. How can I achieve this?
Mohai U Din's user avatar
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ERD Design Question

I am currently working on my database module assignment and have completed the initial design of my ERD (Entity-Relationship Diagram). I would greatly appreciate your insights and feedback on the ...
Hamidreza Maleki's user avatar
2 votes
1 answer
76 views

Deleting a row in one table should also delete the corresponding rows in another table

I have these tables: station and water_types. The user may only have one station, and if the user wants to delete the station, the corresponding water_types must also be deleted. In a station, there ...
JS3's user avatar
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How can I make it so only entities with a certain attribute can participate in a relationship ER diagrams?

I am writing an ER diagram for a pet spa, with pet being an entity as a superclass with the disjoint connection to the subclasses of either cat or dog. A service they can partake in is a massage, but ...
SpiroDouv's user avatar
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50 views

EER Diagramming - Are unlabeled specialization branches overlapping or disjoint by default?

My understanding is when documenting specialization constraints (i.e. Disjointness Constraint) in EER diagrams you label the subclass branches as "o" for overlapping and "d" for ...
Arthur Putnam's user avatar
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How to represent that One entity is not a part of other entity in Conceptual ERD

In a conceptual ERD using crowsfoot notation, How can we represent that one entity is not considered as another entity? I think that if we don't connect these two entities in the ERD, then it is taken ...
Helen's user avatar
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Help needed with database design

I am designing a real estate database to keep records of plots (lands). There are many aspects to it like sale deeds, buyers, sellers, etc. But specifically, the bit where I've got stuck and need your ...
rgarayia's user avatar
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1 answer
39 views

ER Diagram for Missed Visits

I have to design an ERD for a hypothetical scenario. In the scenario, the nurse at a rural clinic needs to get summary data regarding patient visits so she can reschedule canceled or no-show visits. ...
LNicole's user avatar
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1 answer
345 views

Get ERD from my Redshift database

I am a newbie in database management/governance. The problem: I have my companies Postgres RDB in AWS Redshift. So this is not a private project, but enterprise environment. I add new tables/columns, ...
hunsnowboarder's user avatar
3 votes
1 answer
142 views

Need help with first ER diagram

This is my first time doing the diagram. My teacher isn't the best at helping out or responding to questions so I've come here to ask for further assistance. I think I've mostly got it correct, but ...
DataBasedxd's user avatar
2 votes
1 answer
256 views

PostgreSQL partitioned table data model

I have created partition by range based on row_created_tmst for PostgreSQL table. Since partition keys needs to be part of the primary key in PostgreSQL, row_created_tmst is included in the primary ...
Siddharth's user avatar
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1 answer
33 views

ERD Review, Employee travel lump-sum payment based on rank

I'm building application for employee official travel with lump-sum payment based on the employee group or echelon they have and I need a little help how to store the data correctly, as the problem im ...
Hilarius Andriano's user avatar
-1 votes
1 answer
40 views

What arrow is used to specify the relationship between a junction table and the FK tables [closed]

This is part of my first database design. I am unsure what type of arrow to use to describe the relationship: The tables are parking space, parking space features, and features. I am unsure of how to ...
Muffin's user avatar
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1 vote
1 answer
264 views

How to count the number of relationships to a table in MySQL?

I am arranging an ERD diagram of an existing database with about a 100 tables, to add some structure to the process, how rank out the number of relations the tables have to each other? For example, ...
OrigamiEye's user avatar
0 votes
1 answer
844 views

Create an ERD diagram from a set of SQL CREATE TABLE statements

We have a Snowflake database that does not maintain relationships between tables. The lack of relationships is not my decision and I have no control over this. I would like to generate an ERD diagram ...
Calab's user avatar
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3 votes
3 answers
801 views

Is it ok to have repeated values in some of the columns and similar columns in two separate tables?

I'm trying to create database in which I could store thousands of job postings. I put here 3 sample records of these job postings so that you could better understand how everything looks like: Every ...
beginsql's user avatar
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114 views

ERD Review for Chipotle Order System

Attached is the ERD for my attempt at creating an ERD of Chipotles order system. I've been trying to learn how to make good ERD for database design and wanted to get some feedback. I'm confused on ...
Aaron Minky's user avatar
2 votes
0 answers
51 views

One-to-One? or One-to-Zero-or-One?

Scenario: I am being asked to create an HR training tracker for employees of a business. in this database I am using two tables: EMPLOYEE(EMPLID, LastName, FirstName, PrimaryEmail) with EMPLID as the ...
Nathan Willett's user avatar
1 vote
0 answers
50 views

Table for an Appointment App

experts, I am building out an appointment scheduler application. I am seeking advice on how best to tackle this issue. I am building out my ERD and I am the point where I will be creating a ...
Isaiah Melendez's user avatar
3 votes
1 answer
686 views

If an entity's primary key must contain a foreign key, does that make the entity weak?

I'm currently learning about strong and weak entity types in the context of RDBMS. While reading, I came across this statement: "A weak entity is dependent on a strong entity to ensure its ...
Izzo's user avatar
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2 votes
0 answers
199 views

My relational schema and a few questions about relations and duplicate values in columns

I'm trying to create database in which I could store thousands of job postings. I put here 5 sample records of these job postings so that you could better understand how everything looks like: Now, ...
beginsql's user avatar
3 votes
0 answers
52 views

Help Creating a 'Complex' ERD

I am stuck on how to represent the relationships I need correctly. I have a Produce table. Each type of produce—e.g., 'lettuce'—has one or more quantity suffixes that can be associated with it, e.g., '...
KP7's user avatar
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1 vote
1 answer
521 views

How to implement disjoint (nonoverlapping) subtype with total completeness in MongoDB?

I designed an entity relationship diagram (ERD) with the goal of creating two child entities (INSTITUTION and SPACECRAFT) of a parent entity (LOCATION), which is distinguished depending on the value ...
ttoshiro's user avatar
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1 vote
0 answers
814 views

Can a foreign key be a primary key?

I want to know the relationship takes, teaches, advisors tables underlined attributes are foreign key or primary key? or both?
Primer Cielo's user avatar
1 vote
0 answers
320 views

Can I illustrate how a relationship depends on another in an ER diagram?

I'm new to data modelling and trying to build my first ER diagram for supermarket management. My current diagram is based on the following description which I myself come up with: "Suppliers ...
destinical 's user avatar
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1 answer
70 views

There are 2 ERD Designs, and one has a strange combination. I am told both are correct. why?

One of the designs seems clear: A REQUESTEDPRODUCT is picked from STOCK (which has many locations). The primary key is a composite key of 4 foreign keys. The other design is more unclear. The "...
mntblau's user avatar
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4 answers
98 views

Foreign key location

This is a question from a Master's degree. What is the correct response to the question depicted in the image, and why? Or do you believe there could be multiple correct answers?
mntblau's user avatar
1 vote
1 answer
890 views

Chen notation to crow's foot

How do I illustrate relationships which has an attribute in chen notation to crows foot notation? Example: There is an attribute "quantity" in the relation. How do I draw that in crow's ...
Gerome Tahud's user avatar
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0 answers
835 views

Is this ER diagram correct?

I am working on my first ER diagram, for a clothing brand case study. I was wondering if my work is correct. Any feedback is more than welcome. My most important concern is the key relationships ...
Ignacio Clemares's user avatar
1 vote
0 answers
153 views

Fashion Show ERD

working on a class project. Have to make a ERD for a fashion show. Not looking for a super in depth ERD, but one that will give a good grade. I'd like it to be able to Have a 'Clock-In/Clock-Out ...
Richard Sabino's user avatar
0 votes
1 answer
119 views

Is my database ERD well designed

I'm creating a PostgreSQL database for datasets, which should store historical and future data of weather forecasts and train timetables. I'm wondering if my ERD is good enough for a database which ...
Asbee's user avatar
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0 votes
1 answer
41 views

What is the correct usage of IN and ORDER BY keywords when used in conjunction with subqueries?

ERD for my simple db design: I want to order children based on their parent's last name. I am trying to use the following query: SELECT * FROM children WHERE parent_id IN (SELECT parent_id ...
Kapernski's user avatar
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0 votes
2 answers
64 views

Database Design for non-profit family assistance

I have a very basic ERD created for a simple database that stores some information about refuge families being helped out by a non-profit that helps provides some basic needs. ID is the primary key ...
Kapernski's user avatar
  • 127
6 votes
1 answer
3k views

How do I adjust the table link endpoint in PgAdmin's ERD tool after autogenerating it from an existing database?

I can move the lines themselves around, but I can't move the endpoints, which cause the lines to overlap. The only way to understand which relationship is being referenced is by hovering over the ...
Josh Mathews's user avatar
0 votes
1 answer
152 views

How should one design a logical data model for a social platform, or skip it?

After studying from 'Usage-Driven Database Design: From Logical Data Modeling Through Physical Schema Definition'a book by George Tillmann. I want to create a logical model for a my own social ...
Qi luo's user avatar
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0 answers
1k views

Entity relation with itself

I want to make an ER diagram for scientific research papers, one of the constraints is that a paper shouldn't cite itself. I'm not very sure how to achieve this, as this question points out, the ER ...
Chirag Mehta's user avatar
0 votes
1 answer
2k views

How to design a complex multi approval expense db schema in MySQL

I'm very beginner in database design and had the following problem to solve. DB schema design for an expense approval system with these cases approval system, every company has 1 or many teams where ...
reoxey's user avatar
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0 votes
0 answers
1k views

When should I use associative entity?

I am studying DBMS and I have read that associative entity is used when there is a many to many relationships but I am confused with the graph. It has many to many relationships but did not use an ...
zultz's user avatar
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0 votes
0 answers
415 views

E-R diagram 1-to-1 mandatory relationship for two superclass entities to relational schema

How are two superclass entities that are connected to a mandatory 1-to-1 relationship converted to relational schemas? These two superclass entities are also abstract, meaning that they will not have ...
Some1's user avatar
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0 votes
1 answer
19 views

Convert generalization in ERD to Relationnal Database having no additional column

I've a quite simple problem but the litterature I came accross didn't seem to dwell on. Let's say I have an entity OFFER which represents an Offer on a Product, for each product, one offer can be &...
nprime496's user avatar
0 votes
2 answers
202 views

ERD - How to add an attribute to one side of the recursive relation?

The simplified scenario for the ERD A company has employees (each has unique id emp_id) Each employee is supervised by another employee A supervising employee has a special attribute SID Here is my ...
TN_OUSL's user avatar
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