1
vote
3answers
58 views

Best approach for Legal/Natural can have many Orders

I'm working on this model: where as you may see one NaturalPerson can have many Order and the same for LegalPerson the only difference between NaturalPerson and LegalPerson are a few so in that ...
1
vote
0answers
48 views

Relational or non-relational database for a system to pass objects on?

hopefully this is the right place to ask this kind of question. I am working on a system that focuses on helping people give away things that they don't use anymore. So, an object typically has the ...
0
votes
2answers
39 views

What's the use of assigning foreign keys on MySQL [duplicate]

Aside from indexing the value of the foreign key, what is/are the advantage of assigning foreign keys to databases? I've seen a lot of databases that does not assign foreign keys, but is relational by ...
1
vote
3answers
211 views

Heterogeneous ordered list of value

I have the following object model: class A { List<Thing> orderedListOfThings; } interface Thing { } class X implements Thing { int attr; } class Y implements Thing { String ...
0
votes
2answers
28 views

Design for table with multiple links to other table

I am designing a database to keep track of our network equipment. My db has 2 tables: sites & circuits (circuit = cable) & (site = property location) Each circuit runs between two sites, so ...
1
vote
1answer
29 views

Understanding how relationship sides works

So, I have this relations on my tables (see image) and I need to understand some things. I'll enumerate what I understand and what I need from yours is to say if I'm right or not and in case I'm not ...
1
vote
1answer
67 views

Difference between Relational database and time series database?

I have a bit stupid question maybe. I recently came across a term "time-series database". I would like to ask what is time series database and is it same as relational database? Thanks,
1
vote
0answers
98 views

How do you think in NoSQL? [closed]

I'm from the pre-nosql era and am rather comfortable with SQL. However, I cringe whenever someone suggests using a NoSQL database for the "upcoming" project. There are some major problems that I'm ...
0
votes
2answers
57 views

Help required to design a database [closed]

Firstly I would like to apologies if this is not the correct place to ask this question but I know how good community spirit is around here from my time in Stack Overflow. I am very new to the world ...
1
vote
3answers
148 views

Many one-to-many relationships between two tables

In the process of creating a small database for a therapeutic boarding school with Access 2013, I have a problem when designing the relational database model. Two times at least, I ran into a ...
2
votes
1answer
27 views

Save different account types in a database

I have the following issue. In one application (imagine a messaging/e-mail app on your smartphone), the user enters its accounts and gets information from the server displayed. I need to store the ...
0
votes
1answer
115 views

Split MySql table into two tables with One to many Relationship

I have an old database table in MySql. It is used to store the orders from online ecommerce. Simplified diagram looks like this: +----+------+-----------------------+-------+--------------+ | id | ...
1
vote
2answers
59 views

compound primary key with separate id field for reference

I am trying to build locations into a database like so: Country -> Region -> Town Countries will be populated with a list of pre-defined worldwide countries, regions & towns are input by users. ...
1
vote
2answers
169 views

When normalizing a relational database, should multiple “type” tables be combined into one?

Before making substantial changes to the content, functionality and design of my website (I'll be refactoring everything, almost a complete rewrite), I'm setting up a new PostgreSQL database to hold ...
0
votes
1answer
55 views

Relational Model Design - Entity with one attribute

I am trying to desing a database relational model for an assignment. At first, I design the ER diagram and next the relational model with tables(Schemas). So here's my question : Is it possible for an ...
0
votes
1answer
111 views

Airport Database Design guidance required

I am trying to make a generic database for airport management and DBMS would be oracle 11g xe. Since, i am amateur and still learning so i have tried to kept the problem statement simple with limited ...
0
votes
1answer
62 views

Which one is correct and optimized in sql?

Imagine that I have three entities (EntityA, EntityB, EntityC) that can have some images. So there are two ways: Make an image table for each entity. It means that EntityA has a image table named ...
0
votes
1answer
58 views

Create one-to-many to two fields in different table

I have a database where I am trying to figure out how to join a table that contains an object called ModelType. The calibration table contains two fields (EffModel and BkgModel) that are based on a ...
0
votes
1answer
57 views

Attempting to identify transitive dependency

Hello I am attempting to identify a transitive dependency in the following diagram. I think that possibly the determinate of "Subtotal" is "Quantity" and "Price Charged" but I'm not sure if "subtotal" ...
-1
votes
2answers
84 views

What are the possible risks involved in partitioning large database tables? [closed]

There has been much talk about the benefits of table partitioning in Relational DBMS. I would like to know: Are there any risks to table partitioning ? What measures are there to take to minimize ...
2
votes
1answer
65 views

What Happens when Cartesian Product is applied to Relations with same attribute name

I understand that the Cartesian product(X) operation on two databases does not need to be UNION compatible.So,if there is a same attribute called name in the two relations R and S where name in R is ...
1
vote
0answers
71 views

How to join the tables in mysql to get wall messages and comments with name of person ? Only user and his friends messages

I have four tables in my mysql database as shown in the image url provided. I want to select data from the tables without duplication. I want to show messages and comments on wall according to the ...
0
votes
1answer
66 views

Database Designing Issue

I have a database having Millions of records in three tables. Now i want to split these three tables in multiple tables to reduce redundancy and data duplication. A lot of records(Persons) have ...
0
votes
0answers
19 views

Junction table for peer entities and uniqueness for a link [duplicate]

In my database I have two tables: for peer entities (e.g. Persons) and for links between them (e.g. Friendship). Obviously, the latter table contains at least two references to the former table (e.g. ...
0
votes
1answer
405 views

tables for different sources of payments

Selling software products. I have a table "licences". Each software licences is created due to a payment. I am creating tables to accept payments from different sources (e.g. manual or PayPal.) I'm ...
2
votes
1answer
304 views

Relationships between subtypes of an entity

I have a very big (hundred of milions rows) table which represent an entity (event) having many subtypes (different kind of recorded events). Each row is identified by an id (obj_id) and has an ...
0
votes
1answer
50 views

is-a relation(ERM) to tables

i try to design a database with an is-a relation: Vehicles have some general attributes and the SubVehiclesX have some specialized Attributes. SubvehicleX is a Vehicle And a Person has a Vehicle ...
2
votes
2answers
157 views

How to establish a Two-to-One table relationship (PK-FK-CK)?

My question is about DB design and its principles. I am working on a Python application where objects are mapped to database tables. I have Projects and People objects, mapped to their respective ...
3
votes
2answers
121 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 ...
0
votes
1answer
352 views

Advantages of middle tables in one-to-many relationships

Entities: Lists Leads What I am trying to achieve is a scenerio where in the relationship between lists and leads the following constraint is applied: A list can have many leads, but a lead can ...
2
votes
2answers
80 views

Several stays: many-to-many relationship

Could you please help me with the following problem? I'm a total novice in DB design. I have a table with researchers who visit our university. They come for some period of time (from, till). Now, ...
0
votes
1answer
86 views

Index optimization

I'm building a 'tag' system for my blog posts. Currently my tags table has columns tagid - MEDIUMINT NOT NULL AUTO_INCREMENT PRIMARY KEY and tag VARCHAR(30) NOT NULL UNIQUE. And I have another table ...
1
vote
1answer
157 views

Separating tables vs having one table

At the moment I have a table setup that looks somewhat like this: create table tbl_locationcollections ( id int(11) PRIMARY KEY IDENTITY, --(Primary Key), name varchar(100) not null, ...
0
votes
1answer
144 views

Is it better to use multiple one-to-many relationships, or polymorphic?

I've got the following tables: Clicks table Websites table Ads table Both Ads and Websites have many Clicks (i.e. both models have a one-to-many relation with Clicks). In such cases, is it better ...
0
votes
1answer
167 views

Foreign Keys with Composite Key

Imagine I have a table with the following dependency: (Name, BoughtFrom, TimeBought) --> Cost Where the three attributes in bold form a composite primary key for the table. Now then, I want to ...
1
vote
1answer
305 views

Record with variable number of columns?

I am trying to model a cable mapping for devices. Each device has multiple cards, and each of those cards has multiple ports. Since both the number of cards and ports vary, I am confused on how to ...
1
vote
1answer
621 views

Modeling a ticket system based on a set of disparate kinds of tickets?

I'm working on a project that allows for the creation of "support tickets." These are not confined to something that needs fixing, however, so in a way they could more accurately be called "jobs." ...
-1
votes
1answer
130 views

What is the real-world purpose of an optional 1:1 relationship?

I know that one-to-one relationships can be used to split data into multiple tables for performance or security and that it is used to create a is-a-relationsship. But aside from that things, what is ...
7
votes
2answers
408 views

Best relational database structure for this data

I'm in the process of creating a database scheme for the following scenario: There are users Users have roles (such as "Developer" or "CEO") Roles have applications (such as "Topdesk") Applications ...
2
votes
3answers
612 views

Database Design Relationship for Patient Visit in MS Access

I am designing a database to store records for research purposes, and I am having trouble picturing how I can create a relational database based on the information I have. There are a total of 6 ...
7
votes
4answers
229 views

Arbitrarily ordering records in a table

A common need when using a database is to access records in order. For example, if I have a blog, I want to be able to reorder my blog posts in arbitrary order. These entries often have lots of ...
1
vote
1answer
197 views

Database Relational Design for Multiple Categories

I am building a database for participants who are grouped into studies. There's a total of 5 different studies - A, B, C, D, and E. The participants may be in more than one studies, and participants ...
1
vote
1answer
55 views

Correct data model for users with clients

I have an application where users are granted access. Part of the system allows users to have their own 'clients'. I have a users table ******************************** users ...
7
votes
3answers
3k views

How to have a one-to-many relationship with a privileged child?

I want to have a one-to-many relationship in which for each parent, one or zero of the children is marked as a “favorite.” However, not every parent will have a child. (Think of the parents as ...
0
votes
1answer
89 views

Looking for a scalable relational database [closed]

I'm looking for a database that achieves the following: fully ACID. relational with joins. has transactions. allows the administrator to specify sharding rules (for example: users from Europe should ...
0
votes
2answers
343 views

Relationships in a school database

I am designing database for a school app. Student is the main entity in the database. Student has relation with Parent & Guardian. I am confused as where to store references. As will student ...
4
votes
1answer
182 views

How should I model a worflow of status/activities ? (rules like “if is 3 go to 4, if is 4 go to 5” etc)

I'm trying to model a workflow (status and activities) to create "rules". Let me give you an example. The main "object" let's say are "vehicle requirements", I will have this table: idRequirement, ...
1
vote
1answer
104 views

Can I place the attribute in the Entity, when the foreign key is also already present?

I am using DBdesigner Fork for generating ER diagram. I have the 'Company' as an entity for which can I place the attribute of 'idShares', despite of having the foreign key of Shares Entity in the ...
2
votes
2answers
1k views

Database Design - One table for different types of transactions

Considering a procurement system as an example. Would it make sense to have one single table for the following: Quote, Order, Invoice and Credit Memo? There will be some details that are different. ...
1
vote
2answers
97 views

Table Design - Identical tables for different statuses

I am developing a transactional System and the below is a simplified scenario of my problem. Users enter JOBS in a system. A User first enters a JOBS with a DRAFT status (and the Job is given a ...