Category of database management systems characterised by the ability to join two data sets by matching on common fields, using mathematics-based relational logic.

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Diffrence between relational and unrelational database [closed]

What is the difference between relational(MySql) and unrelational database(MongoDb)
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111 views

Need advice on this EER Diagram

This db will work with a CakePhp app and need advice about design. Is it good idea to put orders on center or should I put clients on center? Clients has orders and an order record can only have one ...
2
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2answers
94 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, ...
3
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1answer
550 views

Applying user-defined fields to arbitrary entities

Currently we have an old (rather crude) system that has user-defined fields, which are mapped against rows in arbitrary tables. This was an after-the-fact modification based on a customer request, and ...
3
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0answers
84 views

Table Structure: 2 Related Entities Share the Same Entity

I was hoping I could get some advice on my table structure. Im writing a simple workout tracker for me and my buddies. These are the requirements: Multiple users A user can have multiple workouts A ...
2
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3answers
1k views

First Normal Form, why is it good and how does it reduce redundancy

I asked a similar question on SO and was advised to ask the type of question here. This is for a course on relational databases. A sample problem asks "how come every table in a relational database ...
2
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0answers
713 views

The nature of the relationship between two tables in MySQL

Good day. I'm designing a database for a research project where we're predicting whether or not young female athletes will rupture their ACL(s) based on the nature of a test jump recorded with a ...
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2answers
36 views

Help wrapping my mind around many-to-many relationships

I'm making a database that needs to have the following tables: Article, Video, Image, and Keyword. Keyword contains a fixed list of keywords. (For example when creating an article, you'd have to ...
2
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1answer
38 views

NEWB Getting to KNow New Database and Understand Where Relationships Are

I'm teaching myself SQL using MYSQL and a textbook. While working through the textbook I'm using a database I'm kinda familiar with - an exported copy of my CMS driven websites database. My website ...
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1answer
32 views

related column contents

I've designed a mysql database made of several independent/unrelated tables to use in my office. Different tables hold information about clients (names, addresses etc), visits to the office (dates, ...
19
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3answers
6k views

Proper Use of Lookup Tables

I'm having trouble figuring out exactly how to place good boundaries for when and where to use lookup tables in a database. Most sources I've looked at say that I can never have too many but, at some ...
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1answer
53 views

Bit column vs multiple join tables

I asked a question earlier about how I could define a many to many relationship between users and FOSes (fields of study). My original question was how could we know whether the user was the ...
0
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1answer
301 views

Multiple junction tables?

I am working on a system where you have users, and you have Fields of Study or 'fos' for short. Each user can have many fos and each fos can have many users. So we are dealing with a many to many ...
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1answer
49 views

JOIN to read first table and get possible relationship in the second table

Consider a main table as CREATE TABLE groups ( group_id int(11) NOT NULL AUTO_INCREMENT, group_title varchar(255), PRIMARY KEY(group_id) ) ENGINE=InnoDB and a second table for relationship as ...
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1answer
129 views

How would I change this relational model to fit a nosql database?

Because of things beyond my control, I have to switch from a relational database to MongoDB for the advertising platform I'm helping to build. I've got a relational schema sketched out, but I'm unsure ...
0
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1answer
94 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 ...
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1answer
224 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, ...
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1answer
1k views

Difference in between HAS MANY and BELONGS TO in Yii framework [closed]

I am new to the Yii Framework. I discovered HAS MANY and BELONGS TO in the documentation, however I am confused about these features. Can someone give some real life examples with a diagram that ...
1
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1answer
240 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 ...
2
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1answer
296 views

Switching to NoSQL for native JSON use?

I am rather comfortable writing concrete schemas with explicit primary keys, foreign keys, indexes, views and stored procedures. For queuing I use a NoSQL solution called: Redis. Recently I heard a ...
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0answers
330 views

Use cases for NoSQL databases: Time series

I need to set up a database that will record temporal series data (sensors). A friend of mine has recommended me to use a NoSQL database instead of using Oracle (for instance). There're also some ...
2
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2answers
8k views

MySQL Workbench, how to refresh EER diagram?

I'm using MySQL Workbench to design my MySQL database and model how entities would look like and how they would relate to each other. Now, sometimes I use Doctrine ORM. When using Doctrine ORM, I ...
2
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1answer
679 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 ...
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1answer
591 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 ...
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1answer
200 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 ...
2
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3answers
1k 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 ...
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2answers
582 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 ...
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1answer
343 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 ...
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1answer
63 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 ...
15
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5answers
3k views

What standard should I follow when naming tables and views?

What standard should I follow when naming tables and views? For instance, is it a good idea to put something like tbl_ at the beginning of table names? Should I designate code/lookup tables in some ...
10
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3answers
6k 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
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1answer
105 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 ...
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2answers
521 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 ...
0
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1answer
669 views

SQL Server 2008 - How would I create a dynamic query for finding relationships and references to the primary key?

Since I'm new and I've never shared, and yet there are a few useful scripts that I need on a daily basis, I thought I should. As a new DBA, some data fix DML operations and simple business logical ...
3
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1answer
165 views

Optimised Schema for City-to-City Distance Table

This is my first question, forgive me if this question is simple. I'm stuck here, trying to implement the relations for the data represented below. I want to scale it vertically (new rows), instead of ...
4
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1answer
455 views

database design issue

This is my first time on this beautiful content rich site. I have a sql server 2008 database, but am not too experienced with good relational database design. My project is this: I have a school ...
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1answer
135 views

Relation candidate keys

I have the following relation: R = ABCDE F: AB->DE, AC->B, DE->C, AE->C, C->AB I need to determine this relations candidate keys. Now, if I understood the defintion correctly: ...
4
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1answer
420 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, ...
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1answer
121 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 ...
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2answers
68 views

View for a MANY_MANY_MANY relationship

Let's say I have 3 main tables: category, tag, url category and tag have a MANY_MANY relationship (category_tag). tag and url have a MANY_MANY relationship (url_tag). I would like for a given ...
2
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2answers
2k 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. ...
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2answers
109 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 ...
1
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1answer
2k views

How to model entities in an entity relationship diagram?

I'm a beginner Database designer and wondering if anyone can help me understand this. Let's say we want to design a system that has, among other entities, an entity called Vehicle, and another one ...
2
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1answer
1k views

How do I persist recurring events?

I've been tasked with designing a system to recur events. Events may recur daily, hourly, monthly or yearly. Users should be able to schedule events "every 3rd Wednesday of the month" or "The 1st of ...
8
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1answer
1k views

Friends relations in MySQL

I'm developing a friendship relation in MySQL where friend relation is mutual. If A is friend of B, then B is friend of A. If one of the users end friendship then relation drops. I want to learn which ...
3
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2answers
145 views

Which tables to create according to relations

We are planning a new system with a new DB (MS SQL Server). We have the following entities and the following relations: Entities: Clubs, Chains, PaymentTypes, etc... Relations: Clubs-Chains (M-M); ...
7
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2answers
3k views

Is one-to-one relationship normalized?

Consider we have a large set of statistical data for a record; e.g. 20-30 INT columns. Is it better to keep the entire set in one table as they all belong to a record OR creating a another table ...
4
votes
1answer
126 views

unique constraint on a set

With reference to this SO question, what would be a correct way to implement Unique tag Combination Constraint in SQL Server 2005? To illustrate the problem, I make an example: A tag_bundle consists ...
6
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4answers
436 views

Database Design for updatable sequential records

I am working on creating a data model for storing data related to production tracking. I work for an engineering firm that models and analyzes data for our clients. There are several steps in the ...
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1answer
44 views

What is this type of query called, and how can I formulate it?

I have following tables: events(event_id, name, description) groups(group_id, event_id, title, description) event_group(event_id, group_id) users(user_id, name, email) ...