Questions tagged [subtypes]
Questions about data that is organized into types and subtypes.
90
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Best Practice - Database design for 'conditional join' [duplicate]
I need to create a database to store Jobs.
Each Job can have 1-* Step
Each step is classified as one of either Type A, B or C.
Each Type has specific details and other tables that join on them so ...
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votes
4
answers
27k
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Supertype/Subtype deciding between category: complete disjoint or incomplete overlapping
I'm building an inventory database that stores IT hardware, such as desktop computers, laptops, switches, routers, mobile phones, etc. I'm using supertype/subtype pattern, where all devices are stored ...
CommunityBot
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2
votes
2
answers
96
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Basic RDBMS table relations
If you have a design of a "master table" and several "subtables", is it better* that the master table "link" to each of the sub tables, the subtables link to the master, or for bi-directional links be ...
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answers
136
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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 ...
- 8,520
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votes
4
answers
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Best design to reference multiple tables from single column?
Proposed schema
First and foremost, here is an example of my proposed schema to reference throughout my post:
Clothes
----------
ClothesID (PK) INT NOT NULL
Name VARCHAR(50) NOT NULL
Color VARCHAR(...
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3
votes
0
answers
2k
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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')),
...
- 8,520
2
votes
1
answer
153
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Is it possible to represent a ‘mutual IS-A’ relationship in an entity-relationship diagram?
Is the following scenario correct and why:
A and B are two entities
B is-a A
A is-a B
And what if A, B were relationship?
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3
answers
478
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How can I enforce a one-to-zero-or-one relationship with multiple types?
I am creating a database structure to represent a football league, but there is a certain part that I do not know how to solve, that is:
A member and he can be a referee, a management or a player (...
- 8,520
5
votes
1
answer
5k
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How to represent class table inheritance (current DBMS-specific way please)?
I want to implement class either-or table inheritance (Account, CatAccountDetails, DogAccountDetails) in SQL Server.
I found a recommendation for MySQL:
How do I map an IS-A relationship into a ...
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4
votes
2
answers
3k
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Abstract classes in SQL Server. Are they even possible?
I have a very specific question that I am surprised no one has yet asked. It involves a concrete class model and SQL Server 2016 DDL. The main point is:
In my model, some classes inherit from a base ...
CommunityBot
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21
votes
3
answers
5k
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Implementing subtype of a subtype in type/subtype design pattern with mutually exclusive subclasses
Introduction
In order for this question to be useful for future readers I will use the generic data model to illustrate the problem I face.
Our data model consists of 3 entities, which shall be ...
CommunityBot
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2
votes
0
answers
707
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?
- 8,520
5
votes
1
answer
847
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Implementing a one to one (1:1) relationship between Person and User
Scenario description
I have this person table as super parent (or supertype),
id
firstname
lastname
email
telephone
...
...
and user table as a child (or subtype)
id
person_id (FK)
password
username
...
CommunityBot
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3
votes
1
answer
10k
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Representing a Superclass/Subclass (or Supertype-Subtype) relationship in a MySQL Workbench diagram
Situation
I am trying to figure out how to represent a one-to-one (1:1) relationship regarding a superclass/subclass or supertype-subtype structure in an entity-relationship diagram (ERD) of the kind ...
CommunityBot
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4
votes
1
answer
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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 ...
- 8,520
2
votes
1
answer
1k
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Conditional relationships? One-to-many relationship using a pivot table for only a type of entity
I have the following tables:
users:
- id
- name
- user_type_id (references id on user_types)
neighborhoods:
- id
- name
homes:
- id
- house_number
- neighborhood_id (references id ...
- 5,008
8
votes
1
answer
1k
views
Is my implementation of type/subtype design pattern (for mutually exclusive subclasses) correct?
Introduction
In order for this question to be useful for future readers I will use the generic data model to illustrate the problems I face.
Our data model consists of two entities, which shall be ...
CommunityBot
- 1
5
votes
1
answer
2k
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:
...
- 8,520
0
votes
2
answers
131
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Inheritance of unknown type at creation time
Say I have a table called People into which people are inserted from the moment they are born. Now lets say I want some subclasses of people based on their job. So there are also tables for Plumber, ...
CommunityBot
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2
votes
1
answer
2k
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How to JOIN a table with a name that equals to a determined value in MySQL?
The model of the (PHP & MySQL based) Zend Framework 2 application I’m currently working on contains a inheritance similar to the one described here.
To map this to the database I’m using the ...
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2
votes
0
answers
72
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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 ...
CommunityBot
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5
votes
1
answer
4k
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Many to many between lots of tables?
TL;DR: How could I set up many-to-many relationship between that many tables and is it viable/recommended?
Each body type has its own table
Each car in each body type table can has several features
...
CommunityBot
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10
votes
4
answers
2k
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Don't know how to transform variable entity into relational table
INTRODUCTION AND RELEVANT INFORMATION:
The following example illustrates the problem I face:
Animal has a race, which can be a cat or a dog. Cat can be either Siamese or Persian. Dog can be a German ...
CommunityBot
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5
votes
2
answers
2k
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Modeling a Car Dealership context in an Entity-Relationship diagram
I am creating a conceptual database model for a car dealership. I have spoken to the client, gathered all the requirements, and thought I had my Entity-Relationship diagram all correct; however, I ...
CommunityBot
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1
vote
1
answer
6k
views
Grant execute on specific type in Oracle
I have created a package and defined a type for collections as follows:
create or replace package <schema>.<package> as
-------------------------------------
type <type> is ...
CommunityBot
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2
votes
1
answer
99
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Using the same table for entities that are almost alike when it breaks foreign key integrity?
I'm designing a website with a database that should support events that a user can sign up for, fx. a concert. Users can sign up using our internal registration system, or using an external website (...
- 1,513
0
votes
1
answer
2k
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Derived classes with same base class and class specific ids
I have three classes in my project. One base class and two derived classes.
public class Animal
{
public long Id { get; set; }
public DateTime Created { get; set; }
public string Name { ...
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5
votes
2
answers
2k
views
Best way to linking different entities to a single table
I'm running for office and have created a web app for tracking my door knocks to voters at their homes. The database contains a table called voters that contains all the necessary information about ...
CommunityBot
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3
votes
3
answers
1k
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Field types database design best practice
I am creating a cms system where the user can create fields to use in the templates of the website. I want to create different types like 'string', 'html', 'integer' etc. The user must also have the ...
- 5,043
4
votes
1
answer
2k
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Enhanced ER Model Supertype / Subtype modeling issue with inheritance and recursion
Before posting, I have looked for a good solution on internet and I have coined this post for 3 days in row and trying to think through it prior this post. So if I have missed something or got it ...
CommunityBot
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2
votes
2
answers
1k
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Normalising shared entities and applying constraints
I'm looking for a specific "best practice" or "pattern" concerning entities that are shared between different entities, having a relation to one of many.
For example, one may have the generic entity "...
3
votes
1
answer
57
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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 ...
- 24.8k
3
votes
1
answer
3k
views
Supertypes and subtypes
I am trying to design a database that has supertype/subtypes. I have the following users:
- basic user
- business user
- administrator (super user).
All three users share a common table (users) ...
CommunityBot
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2
votes
1
answer
3k
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Foreign Key Constraint over two tables
I am trying to put the following entity-model into practice:
We have a list of Payments, each Payment belongs to a certain store and is of a certain payment type (e.g. 10€ maintenance cost in Store1, ...
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2
votes
0
answers
918
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 ...
- 23k
0
votes
1
answer
92
views
Normalization for three somehow identical tables
These three tables are nearly identical. But, there are some exceptions.
But, I can't find best normalized structure. Could you please help me?
Here is the informations must be hold in database:
1)...
- 2,776
4
votes
2
answers
1k
views
How to enforce data consistency across one-to-one relationship in an inheritance hierarchy
Consider this design for a typical school database:
Person:
-----------------
FirstName
LastName
SocialSecurityNumber
Phone
Email
Student:
-----------------
Grade
Teacher:
-----------------
...
- 4,316
1
vote
0
answers
68
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,...
- 6,208
0
votes
1
answer
56
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Additional info on some rows in the table
I am trying to design an MS Access 2013 database to keep track of an inventory of items.
All items have certain common properties, like name, date they were stored, location of the physical item, etc....
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3
votes
3
answers
4k
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Database design: 4 types of users but have different functionality , separate or one table?
I have 4 types of users:
Admins , normal user , company , service provider
Admins and normal user share some attributes (id .first name ,last name ,phone ,mail) company and service provider share ...
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