Questions tagged [subtypes]

Questions about data that is organized into types and subtypes.

20 questions with no upvoted or accepted answers
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Supertype table with disjoint subtypes in MySQL

I want to have base parent table with few disjoint subtypes. To illustrate what I mean: CREATE TABLE issues ( issue_id SERIAL PRIMARY_KEY, issue_type CHAR(1) CHECK (issue_type IN ('B', 'F')), ...
3
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0answers
128 views

How to relate a "parent common" table with its (possibly many) "subtype" tables?

I am having a bit of a brain freeze. I have a table whose properties are the root of four distinct elements, for example: I need to relate SystemType to a SystemCommon, where one SystemCommon can ...
3
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1answer
49 views

Confused about what to use to create the data

I want to create a database for myself. The data has complex grouping. I don't know which system to use to create my database. The data is in groups and sub-group forms, it almost has 5-6 layers of ...
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0answers
570 views

What is the difference between (Superclass/Subclass) Total and Partial Specialization?

What is the difference between total and partial specialization of superclass/subclass (or supertype-subtype) structures in enhanced entity-relationship modeling?
2
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0answers
63 views

Looking for suggestions to model a database of Electrical Components

We have a database of electrical components and I am trying to make sure I have a good design. I am not a database designer (my comfort zone is designing with these hardware components), so I am ...
2
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0answers
890 views

How to store data where various subcategories have specific columns?

I'm new to database designing. I'll use MySQL and PHP. I'm designing a database in which I have a lot of categories and subcategories like given below: Product Table p_id p_title category_id ...
1
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0answers
317 views

Schema for social network using the supertype/subtype pattern

Scenario I'm trying to come up with a schema for a kind-of social network app, where users can publish Posts (and photos inside Posts), and also manage a private Diary that has also Posts (not sure ...
1
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1answer
196 views

How to handle a table schema with a new relationship subtype in an interviews scenario?

I have a table of "interviews" and "interview reviews" for both the interviewer and the interviewee. When the project was started there was only the need for one type of review, which is shown below ...
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0answers
269 views

How to create entity-relationship diagram for tables that can potentially be united by an "IS A" relationship?

I have this schema: create table hall( building-id int, hall-id int, capacity int, primary key(building-id, hall-id) ); create table semester( sem-id char(5), start-date date, eend-...
1
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1answer
63 views

How to make Event (like a Party) Sources mutually exclusive?

I'm designing an entity-relationship diagram (ERD) for a marketplace of events. An event can be created by a user, in which case the Event table must have owner_id or we pull it from an API in which ...
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0answers
53 views

ERD Design issue - general/central projects table

I have multiple different “project manager” apps as: Work Projects app manager, Home Projects app manager,... Each app has its own DB i.e separate ER diagram. Each app has it's own [projects] table(...
1
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2answers
345 views

Modelling users and groups - but with multiple types of groups

I'm modelling a user management system in PostgreSQL that is fairly typical in that it consists of users, groups and permissions (and the relationships between them). However, its seems I'm dealing ...
1
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2answers
125 views

Need help making a sane database schema

I am writing a backend for an application that has 4 main types of content: a message, a post, a thread, and a thread reply. Right now, these are all stored in separate MySQL tables: a table for each ...
1
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1answer
287 views

Category entity relationship / subtype relationships design

I am looking to implement a generic comment and file attachment facility within a web application which would be used across various parts and allow users to provide comments and add attachments to ...
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0answers
65 views

Help with ER design

So i am trying to create a db for a restaurant as a homework assignment.. However there is a spot that confuses me and involves the dish entity. "Every dish must belong to a category (soup,...
0
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3answers
173 views

How can I design Person table in MySQL?

I have two person type: Users and Clients. Users can login the panel but clients can't login the panel. My current database: (but this design not good for me. I need to connect these tables to the ...
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0answers
16 views

Trouble with inheritance: Separate table implementation for disjoint entities and common ID

I currently have four disjoint entity types (competition, talk, award, publication) that are to be converted to tables. In order to manage certain other data for each, i.e. documents related to each ...
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0answers
28 views

Does "Inheritance" Make Sense with This Requirement?

I'm using Oracle 12c. Given an existing table (we call it TBL_M), and based on the criteria below, I was wondering if using inheritance makes sense to lay out the entities: Information for one group ...
0
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1answer
203 views

How to create a SELECT statement involving a subtype

Okay, so all I'm trying to do here is "list" the managers who supervised the employee that charged a customer $100 for a rental on November 1st, 1998. My issue is that I don't know how to select the ...
-1
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1answer
64 views

Is there a best practice design for handling different types of the same object which have different properties?

This may be a rather naive question and I am not even sure if I am asking it in the best way, so my apologies if not. I would like to know if there is a standard, or best way to handle cases where ...