Questions tagged [erd]

Entity Relationship Diagram

Filter by
Sorted by
Tagged with
30
votes
10answers
897 views

What is an effective way of labeling columns in a database?

I used to label columns in my databases like this: user_id user_name user_password_hash To avoid conflicts when joining two tables, but then I learnt some more on how to alias tables, and I stopped ...
17
votes
2answers
10k views

Implementation of a many-to-many relationship with total participation constraints in SQL

How should I implement in SQL the scenario depicted in the following Entity-Relationship diagram? As it is shown, every A entity type occurrence must be related to at least one B counterpart (...
13
votes
2answers
2k views

How to structure a model to properly and efficiently represent tree-like data on relational databases?

Based on Traversing tree-like data in a relational database using SQL question, I would like to know how the way regularly used to describe tree-like data on relational databases considering physical ...
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 ...
12
votes
2answers
1k views

Best data modelling approach to handle redundant foreign keys in a database about Surveys, Questions and Responses

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 ...
12
votes
1answer
6k views

How do you represent VIEWS in an ERD?

Are VIEWS (CREATE VIEW) represented in an ERD? If so, how do you represent them and specify what tables they came from?
11
votes
2answers
1k views

Conceptual ERD Multi-table many to many, or possibly recursive?

I'm creating a conceptual diagram [yes, I know I've included attributes and keys - but this is just for me to consolidate what I'm doing whilst learning] -- so please treat it as Conceptual with the ...
10
votes
5answers
17k views

Importance of ER Diagrams

I am a student and I am developing several projects as a part of my academia. While developing the database for one of the projects, we came across a situation where we thought about whether ERD is ...
9
votes
1answer
27k views

How can I import the contents of an Oracle database into Visio to create an Entity Relationship Diagram?

I have an Oracle database, and I would like to create an ERD in Visio 2007 Pro. I have so far looked at DBMS_METADATA.GET_DDL commands to generate DDL. I know that I can import an Access DB into ...
8
votes
2answers
20k views

Is it OK to have an entity in an ER diagram without a relationship?

I'm creating an ER diagram for a class assignment and I was wondering if it would be possible to create an entity that had no direct relationship to any other entity, and simply use foreign keys to ...
8
votes
1answer
4k views

How are indexes represented in an ERD?

What do indexes look like in an Entity Relationship Diagram? I've googled it and I'm unsure what the standard look of an index is in an ERD. And I'm talking about the crowsfoot diagram that includes ...
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 ...
7
votes
3answers
6k views

Need help on my first ER diagram

I just started my first Database course online, and I have a homework assignment to create an entity-relationship diagram (ERD) from a list of specifications. The specs are as follows: The company ...
7
votes
1answer
1k views

How to model a Letter Transportation business context in a database diagram?

I am trying to crate entity-relationship diagram for a transport company database. This database should store information about letters, deliveries, moving letters from one warehouse to another, and ...
6
votes
3answers
854 views

How to model Parent -> Child -> Grandchild if the Child can be removed

I'm dealing with a set of relationships where the child can be removed, but I obviously don't want to lose the connection between the grandchild and the parent. I did think about marking the child as "...
6
votes
8answers
60k views

How to export an ER diagram from an Oracle DB? [closed]

I am developing this application with an Oracle database. I haven't been documenting the data model, but now an auditor wants to have an entity relationship diagram of my database. There are many ...
6
votes
1answer
3k 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 ...
6
votes
1answer
627 views

Entity-relationship diagrams and application program functionalities

It seems that the core functionalities of an application program I'm working on are nothing but associative entities. Hence one-to-many relations sort of produce "metadata" that will only feed (one ...
6
votes
2answers
762 views

Design: How do you decide when items are related vs when they are attributes?

I've been trying to figure this out for a while. Let's say you have a person, for example. An attribute of a person is his or her social security number, right? But a person also has a social ...
6
votes
2answers
12k views

Should ERD derived attributes be included in logical tables?

I have created my entity-relationship diagram (ERD for brevity) and it has derived attributes. When it comes to database design using a relational schema, I've designed my tables and linked ...
6
votes
1answer
1k views

Postgres 9.6 export the database structure as pdf [closed]

Is there any tool/software the can export all the tables structure (column names , its datatype ) in the database as a pdf/excel/word. additional diagram export will be added advantage.
6
votes
2answers
2k views

How do I create a user invitation model?

I am developing an application which allows 'users' to create 'lists'. I have a many-to-many relationship between 'users' and 'lists' (this might not be right). Additionally 'Lists' have many 'Tasks'. ...
6
votes
0answers
2k views

Working on a decision tree database design

I'm doing the conceptual model for a Decision tree database. The goal is store any Decision tree. I have four entity types: DecisionTree, Node, Branch and Leaf. Each Decision tree is composed of ...
5
votes
3answers
6k 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
3answers
2k views

Are there any tools to go from ERD to DB design and vice versa? [closed]

I'm learning DB design and looking for some tools, preferably open source software, that could help go from an ERD to a DATABASE and vice versa. For the record, the database i'm using is MySQL.
5
votes
3answers
892 views

how do I model this in database?

I am using mysql as my backend database. Here is the use case; A HolidayPackage is configured with some default offerings. These default offerings can be up/downgraded based on the options provided. ...
5
votes
2answers
340 views

How can I represent the entity types depicted in an ERD as relations with attribute names?

I have created the entity-relationship diagram (ERD) shown below (for brevity, each individual bubble-shaped box portrays multiple attributes): Considering such an ERD, I have to convert each entity ...
5
votes
1answer
2k views

How to enforce a constraint over multiple tables?

I have the following five tables: PRODUCT FEATURE PROVIDER PROVIDER_PRODUCT PROVIDER_FEATURE The logic is as follows: A generic PRODUCT can have one or more FEATUREs. There are different ...
5
votes
1answer
2k 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 ...
5
votes
4answers
9k 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 ...
5
votes
1answer
885 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
12k views

Tool for Reverse Engineering of PostgreSQL Database on Linux (Ubuntu) [closed]

Please suggest a tool to reverse engineer a PostgreSQL DB into an entity-relationship-diagram (ERD) or equivalent ?? Ideally, I'm looking for a simple ERD or UML class diagram in a format that is ...
5
votes
4answers
3k views

How can I generate an Entity-Relationship Diagram and SQL DDL statements from natural language text?

I am using LaTeX or another text-macro tool/library. How can I (1) use natural language text to describe relationships, then (2) generate an Entity-Relationship Diagram and (3) generate SQL DDL to ...
5
votes
1answer
1k views

Is my entity-relationship diagram about customers and accounts correct?

Business domain description Each customer has a name, a permanent address, and a social security number. Each customer can have multiple phone numbers, and the same phone number may be shared by ...
5
votes
1answer
2k views

Payment methods conceptual and logical model

I need to create a conceptual and logical (normalized) models of parking house according to the requirements below. It looks to me as a very simple concept that doesn't need all tables to have ...
5
votes
2answers
2k 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 ...
4
votes
3answers
5k 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: Figure ...
4
votes
2answers
10k views

Can a weak entity have a primary key?

Sorry for probably a very basic question, but in the literature and online, I have came across two different definitions of weak entities, which may sometimes be contradictory. 1) Weak entity is an ...
4
votes
2answers
4k views

Is my ER Diagram correct? Why use relationships?

This is the first time I've made an Entity Relationship Diagram (ERD) for database that will be built on MySQL. The business domain of relevance is about equipment issues management. Prior to this, I ...
4
votes
3answers
2k 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 ...
4
votes
1answer
402 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-...
4
votes
1answer
687 views

Modeling Subclass (or Subtype) Constraints in an Entity-Relationship Diagram

Scenario description Can someone help me out on how to model the situation that follows: There is a superclass (or supertype) called PRODUCTS, which has the subclasses (or subtypes) named FOOD and ...
4
votes
1answer
2k views

ERD via Chen's notation: How do I organize multiple 'last done' entries?

I'm having an issue creating a little practice ERD. I'm trying to do some more difficult stuff, and I'm not sure what the standard way to organize it is. Basically, I don't know which of these is ...
4
votes
2answers
274 views

How do you read a one-to-many relationship in both directions?

I'm having issues with reading this relationship. Let's take the Professor and Class entities in this example. If I read this from Professor to Class, I would say, "A Professor teaches one to many ...
4
votes
1answer
906 views

Designing a database which can track stock movements

I work for a manufacturing company which sells machines to customers which have a control unit installed in them. We need to keep track of the locations of all the Machines after they are sold to the ...
4
votes
1answer
473 views

Do I relate entities that are indirectly related when creating a student-course ERD?

I'm trying to create an ERD for a tutor center, this is what I understood from their operations: There is the tutor center director, then under her there are sections/departments. It, math/calculus, ...
4
votes
2answers
232 views

Can relationships have relationships?

I have the following requirements (as part of a larger system). In the database, I need to maintain a list of parts, suppliers who sell those parts. Many suppliers can sell the same part and each ...
4
votes
1answer
2k views

Modelling Relationships in an E-R Diagram, Table or Foreign Key?

Should a relationship in an E-R diagram be created in the database as a table or a foreign key? For example: a tutor lectures a class I see it as three possibilities: there is a "lectures" table ...
4
votes
2answers
423 views

Should a composite primary key out of 3-4 attributes or a unique artificial ID should be used for the situation below?

For a small beginner project to start with databases and system development, I'm trying to develop a system that represents the classic case of an administration system for students and exams. This is ...
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: ...