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

learn more… | top users | synonyms

0
votes
1answer
80 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
123 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, ...
-1
votes
1answer
677 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 ...
0
votes
1answer
107 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 ...
1
vote
1answer
189 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 ...
0
votes
0answers
132 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 ...
1
vote
2answers
4k 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 ...
0
votes
1answer
126 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 ...
2
votes
2answers
214 views

MySQL - Normalization over meaningless data - Compound Primay Keys or Surrogate ID field

Please forgive my title; if you have a suggestion for it, feel free to comment. I have a database: DROP TABLE IF EXISTS `books`; CREATE TABLE `books` ( `isbn` VARCHAR(255) NOT NULL, `title` ...
1
vote
1answer
192 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
votes
1answer
112 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
votes
3answers
468 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
2answers
331 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 ...
7
votes
3answers
173 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
150 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
52 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 ...
13
votes
5answers
1k 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 ...
7
votes
3answers
2k 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
85 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
236 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
votes
1answer
351 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
votes
1answer
112 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
votes
1answer
430 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 ...
1
vote
0answers
419 views

Which database technology for big structured data? [closed]

Scenario: Think you have got 100TB of text in 200 tables. This is structured related data. compareable to dbpedia only more data. Any really relational and distributed and performant database would do ...
1
vote
1answer
94 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
votes
1answer
150 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
97 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 ...
0
votes
2answers
63 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
votes
2answers
721 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
88 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
vote
1answer
907 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 ...
1
vote
0answers
107 views

SQL relationships, one-to-one, many-to-many etc [closed]

I'm trying to understand all relationship types that can be created in SQL. So far I only get the "belongs-to" one - Example: a table with "Blog post" records, which contains an author_id column that ...
2
votes
0answers
1k views

Schema for an RBAC (Role-based Access Control System)

I want to implement an RBAC, Flat based. I've decided to base my system on the NIST standardization model. Although all fine and well, I have an inclusion to that design. Instead of a hierarchy ...
1
vote
1answer
790 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 ...
6
votes
1answer
314 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
votes
2answers
137 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); ...
4
votes
1answer
1k views

Designing a user authenication (Roles & Rights) module

I am trying to model a User Authentication module for a MS SQL Server database that will be the back end to a Delphi UI Application. Basically, I want to have user accounts where the user belongs to ...
6
votes
2answers
1k 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
117 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 ...
1
vote
1answer
221 views

What is the correct way to store a list and its items in this instance?

The app I'm working on revolves around projects. Each project can contain several lists, and each list is made up of several items. Each list relates to a single project. Is it better to have one ...
5
votes
4answers
238 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 ...
1
vote
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) ...
4
votes
1answer
130 views

How can I improve this design?

I'm creating an event planning PHP/MySQL web application as a learning project. The whole app revolves around the idea of the event and its various components (participants, groups, lists, etc.) I ...
4
votes
1answer
399 views

How to use a relational database to store all users who belong to a group, and all groups which a user belongs to?

This is a beginner question: A user can belong to many groups, and a group can contain many users. Let's say the two tables look something like this: user_id user_name user_email group_id ...
2
votes
2answers
189 views

mySQL Relational Tables

Say I have 3 tables Products, Orders and Orders Product Products Table ID | StockNum | Description | Price 4 | 452SB | Black | 45.65 5 | 752SA | Green | 17.12 Orders Table ID ...
7
votes
2answers
1k views

How do Application Like Yelp Retrieve distance information from data base efficiently

For example, say I have a table: Business(BusinessID, Lattitude, Longitude) All are indexed of course. Also there are 1 million records Say I want to find businesses closest to 106,5, for example, ...
5
votes
1answer
280 views

Database structure, relational or data warehouse?

Good morning, Im having some issues with how my database should be laid out and would appreciate some guidance. I have several tables (rainfall data), each containing the following columns: Date ...
6
votes
2answers
619 views

What's a good relational structure for units and complex unit conversions?

My company is in the Energy industry and I need to come up with a good way to represent the conversion of units of measurement. I've done some searching and have yet to find a good article covering ...
2
votes
3answers
322 views

Express union which is dependent on other results

I would like to make a union of two tables that are actually in a hierarchical constellation. How would I write that in relational algebra? Say table A is the parent of B in a 1:n relationship. ...
1
vote
1answer
404 views

Insert bulk Parent and Children rows using SQL Query

We receive bulk data from our customers in a spread sheet. I loaded them in a temporary table as of now. I tried to normalize the data and create a parent table and each parent to have 4 or 5 child ...