Newest 'entity-relationship' Questions - Stack Overflow

Questions tagged [entity-relationship]

An entity-relationship model (ERM) is an abstract and conceptual representation of data, information aspects of a business domain or its process requirements. Ultimately ERM is being implemented in a database.

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How to create a ER diagram (entity relationship) from normalized data?

I am given an example of an invoice for buying a car and required to normalize the data(taking the fields from the invoice)and create an ER diagram. I normalized the data (0NF,1NF,2NF,3NF) but I am ...
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Manually creating a 0..1 to 0..1 relation in Entity Framework's Database First approach

On my database, I have one table which contains a list of trailes, one for loading bays and one connecting table. The latter contains a list of when which trailer was at which loading bay. So far, so ...
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EER diagram - How to represent supervisor can perform all tasks of other roles

I am drawing an EER diagram to represent the following relation. The employee can be either supervisor, clerk, assistant or HR. But supervisor can perform all tasks of other roles. Am not sure whether,...
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How to create a good ER model for this program (Questions about my ER model)

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 ER model and if it's entities and relationships are ok. This is an application ...
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How to migrate EF 4 to EF 6

I have a project which currently uses EF 4.0 I want to migrate this project from EF4 to EF6. What is the best and the easiest way to do so? All the answers that I have come through right now seem a ...
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Room SELECT for “many to many”

Let's assume i have the following entities: Entity A: @Entity( tableName = "a_table" ) data class A( val name: String ) { @PrimaryKey(autoGenerate = true) @ColumnInfo(name = "a_id") ...
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ERD: Will a relation between two entities only exist if entity 1 has a foreign key that identifies from the primary key entity 2?

I will make an ERD, but from some examples from the tutorials that I have read are different and they do not explain conditions so that the relationship stands between 2 entities?, Is it because their ...
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How to take decision while developing web application using microservices in spring-boot for common code and relationship

I am going to develop small web application to get an idea of micro-services architecture, using spring-boot and spring-data-jpa. At initial stage, I have only 2 entities (1) CountryEntity and (2) ...
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SQL Table Design for Reporting

I am building a platform that allows users to report posts/messages/events/etc. Each of these have their own table with their own id. How do I design a report table that allows users to report any of ...
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NPOCO. Is it possible to insert nested objects?

I have a Dto class with two nested Dtos: [TableName("ProductComponentVariant")] public class ProductComponentVariantDto { [Column("Id")] public int Id { get; set; } [...
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Does an official entity-relationship diagram for the GTFS exist?

Here is a reference on the different csv files composing a dataset conforming to the General Transit Feed Specification (GTFS). Unfortunately the documentation lacks the entity-relationship diagram ...
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Entity relations in an ERR diagram

I'm looking at creating an allocation system which will assign teams to turnarounds. A team has colleagues which have skills. A team must have certain skills. A turnaround has one or more inbound, ...
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How is this schematic supposed to look? EERD modeling

I dont understand how it is supposed to look completely, this is the case study: Each store is also assigned a supervising store where all training is conducted, and server applications and help desk ...
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Copy n to m relation in MySQL

Suppose I habe two tables recipient and list. recipient has the columns id, email and customer. list has the columns id, name and customer. Both tables are connected via recipient_list with the ...
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Confused on ER examples

So I'm a bit confused on how ER diagram relationships work. The examples provided by my professor are a bit confusing (we don't use crows feet notation) so I was wondering if anyone could help me ...
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How to avoid duplicate data in one-to-many relationship

Consider a following case: there is an Action table, which has fields - id, start_time, end_time and group_id. there is an ActionGroup table, which has fields - id, start_time and end_time of a ...
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Is my ER-Diagram for yearly data on trade and transportation OK?

As part of my school project, I'm supposed to design/make a database where one can store/update/retrieve yearly data about international trade and transportation. To begin with, I isolated a small ...
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Best way to model relation between a parent document and one split out child document?

Requirements Documents of type project always have a relation to exactly one document of type quotation. Two projects cannot have a relation to the same quotation. Two quotations cannot have a ...
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Jpa Entity conditional relationship mapping?

I have Person Class and Zone Class. If Person Type is RESPONSABLE a One To One BiDirectional should be applied. If Person Type is GARD A MANY TO ONE should be applied. is there a way to achieve ...
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What is the meaning of the rhombus symbol in a SQL Server ER Diagram?

What is the meaning of the rhombus symbol in a SQL Server ER Diagram? I have found this picture of a relationship with rhombus symbol. However in SQL Server Management Studio (SSMS) 2008, 2012 and ...
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Recommendation || How should a database object that moves through phases be represented in a database model?

I am new to working on databases and am currently working on a database model for a project management tool. Is there a convention for representing an object that has different phases with different ...
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Worker information: ER diagram and table creation

I want to develop a database for storing workers' information. For now, I have these informations for each worker: name, current job, contact, birth day, weight, height, past job experiences, ...
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Design a good entity relationship model for a process focus area

I am designing a relational model that allows me to see the relationship that exists between the different processes, the programs that are used in each process, the services that each process ...
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How do you trigger one to many relationship between (many to many) table and a normal table?

I am trying to make one to many relationship between Contacts table and DepartmentTitle table. I was thinking of introducing surrogate key on DepartmentTitle table so that I can reference this ...
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Which entity relationship method looks right or better?

I see that there are two different ways to make entity relationship on the example illustrated below (either by one to one or by many to many). Which one is better method? (What is the better method ...
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Is there a general method of relation decomposition for any n-ary relation?

I know that there is a way to decompose a ternary relation into binary relations [1]. However, is there a way to either: decompose any n-ary relation into m-ary relations for m < n, Or check ...
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Is there any way to have ER diagram with relationship connectors for the MySQL database schema?

In MySql, I have to generate/draw an ER diagram which having the tables and their relationships (the primary key & foreign key). I tried it with MySQL Workbench by the Reverse Engineering option ...
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Cannot use table 'Accounts' for entity type 'User' since it is being used for entity type 'Address'

I am losing my mind right now. I am trying to model my database model with navigation properties that exist on both child and parent identities. Meaning, the parent has a nav property pointing to the ...
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Is a foreign key constraint on a table created just to resolve a multi valued attribute good design?

In my ER model, I have an entity type 'City' which has a multi valued attribute of ZIPCode. So far, so good. Now when, I translate my ER model into relational schema, I create an extra table to ...
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Making an ER Diagram for a discount broker like Charles Schwab

I am working on an assignment where I have to design a database for an online discount broker. The first step is to plan it out as an ER Diagram based on details given. Here are the details: Here ...
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Modelling a daily event with Entity-relationship diagram

I am new to ERD and I have been tasked with creating a ERD of a store chain. The chain contains several stores which all have several items being sold in them. After every day every store is supposed ...
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Relationship attributes having relations with another entity

I am creating an ER Diagram for an assignment using UML and cannot find much information on using relationship attributes. Can relationship attributes have relations with another entity? I have drawn ...
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How to pass a data from formType parent to formType child

I have a form that takes place in several stages, including : Step 1 : a simple form, based on an entity 1, which records a first part of the dataset. Step 2 : a parent form (based on entity 1 in ...
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Can i have 2 ER diagrams for one database

The database I have set up is accessed by normal users and an admin with both user types having different permissions. Should I have 2 ER diagrams? The relationships I've worked out are as follows: ...
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Different relationship between 2 entities

In my project I have a part where says - An airline has many flights and each flight has one source (airport) and one or more destinations (airports). For each source destination pairs, you have ...
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Toad Notation - What do (Ix#)'s mean?

So, I'm trying to visualize a database, and I have some tables put together which consist of a mix of object-oriented and relational; just trying to tie them together. My issue is, I can't seem to ...
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Does MySQL Workbench Diagram Maker allow for relation tables?

I'm making an ER diagram in MySql Workbench, but I don't see an easy way to connect tables satisfactorily. What I want is something like this: which I am able to do for single relationships with a "...
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How Laravel defines name of the foreign-key as default in Model file?

I am new at Laravel and I am wondering how actually Laravel determines default foreign key name. According to the Laravel document, it says "Eloquent determines the default foreign key name by ...
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weak entity depending on either one of two other entity

Consider that we have employee as an entity and it's family member as a weak entity. We want to have family members health record. so we add another weak entity "Health Record". The ER diagram would ...
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A 1:1 relationship with auto update/insert semantics (Fluent API)

I have plenty of ways to implement around this, but I'm curious about whether or not one specific implementation is possible in EF6 using the Fluent API. Take the following two classes as a starting ...
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Modelling multiple many-to-many relationships in Dynamodb

I am trying to model the following relationship in a single Dynamodb table. User -> many to many -> Game User -> many to many -> Group In words: A user can have many games, and multiple users can ...
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Filter in ERD-Diagram

could someone help me with this problem. I have some "filter-options", its RANGE and CODE. With these filters i have to inner-join the BOOST-Entity on RANGE and CODE to get RESULT1. Now i have to ...
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Modelling Relational Data in Firestore with Angular

I am aware that there are plenty of questions asked to this topic, but the other questions do not seem to answer my rather case-specific one. I have the following Structure: Each User via FireAuth ...
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Many-to-many relationships with EF Code First and multiple schemas

I am trying to create a db structure using multiple schemas. I am now at the point where I need to link my User table (authentication schema) to my TrafficArea table (assets schema). However when ...
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How to properly model Recursive category in er model?

I would like to know, how to properly show recursive categories in er model? I have table Employee with details such as Name, Age, Email etc. and I have self-reference with EmployeID which means ...
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Represent a route in er diagram that is dynamic

I have to implement a faculty system where if a faculty wants to apply for a leave, his leave application follows the path Faculty -> HOD -> Dean -> Director So, I have to store this route in an ER ...
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How to write nullable properties for EF6 table definition class with C#?

I want to write an C# class to describe a database table with an relation to itself, later to be used with Entity Framework 6. I have the following C# code to implement the above shown table: public ...
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Should I model the database admins in my ERD/relational diagram?

I'm trying to model a database (for my assignment) that involves two user groups that post content to the platform. A third user group would be the system/database admins that are responsible for ...
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Entity or relationship

I am drawing an ER diagram. Movies (title, year, and rating) are shown in theaters (name and city). A movie can be shown in many theaters and a theater can show many movies. "Show" should hold ...
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I need to relate a table that is created from a relationship with another table that is created with another relationship

the teacher of a subject in a classroom, which is in the relationship N: N: N, makes many assessments of many students. I do not know how to create the table to let me do this.