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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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
147 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
452 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
119 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: ...
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277 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
116 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
66 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 ...
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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. ...
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2answers
104 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 ...
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1answer
1k 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 ...
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0answers
141 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 ...
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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 ...
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817 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 ...
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2answers
144 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); ...
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2answers
2k 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 ...
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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 ...
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1answer
532 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 ...
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4answers
398 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) ...
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1answer
140 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 ...
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1answer
643 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 ...
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2answers
209 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 ...
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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, ...
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320 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 ...
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2answers
807 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 ...
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3answers
404 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. ...
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1answer
612 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 ...
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1answer
759 views

database functional dependency candidate keys

How do you know when you found all the candidate keys in a functional dependency? I know how i would go about finding a candidate key, just don't know how to tell if there are more. Thanks.
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1answer
443 views

Would appreciate some suggestions on how I should model this data

I am setting up a website that will have users. Users can search for songs and (if signed in) save them to a playlist or their library of songs. I want it to be like iTunes in that all the songs on ...
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4answers
11k views

How should I design a relationship table for friendship?

If A is a friend of B, then should I store both values AB and BA, or one is enough? What are the advantages and disadvantages of both methods. Here is my observation: If I keep both then I have to ...
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3answers
245 views

How to design this simple DB?

How to design this simple DB? I need to add some things to a DB I use to keep track of servers. Table looks something like this. Matrix | Name | Description | Etc | Etc | ...
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1answer
762 views

Relational algebra question

Here is the relational schema given : employee (person-name , street, city) works (person-name, company-name, salary) company (company-name, city) manages (person-name, manager-name) Q: Find the ...
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2answers
341 views

Definition for “logical difference”?

I'm currently reading "SQL and Relational Theory" by C.J. Date. And although I'm quite far in the book, I've got a few basic questions. I want to know what the term "logical difference" means, The ...
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1answer
167 views

How can I best combine “get categories” and “has user access”?

I was wondering if it's possible to create a query for the following problem. I only want to select categories from the (MySQL) database (if the user has access). A user has multiple roles; A ...
6
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3answers
1k views

How to normalize Time Sheet data?

I am having a terrible time finding an appropriate way to store this data in a database. The current excel (simple) version looks something like this: http://i.stack.imgur.com/BEZOw.png Staff and ...
0
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1answer
816 views

Database design for head to head sports

I am trying to create a database to store details relating to darts matches. Im relatively new to this so was wondering if the design I've come up with below would work. It seems I have lots of places ...
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1answer
271 views

How to design relationships for variant data?

Help me define the table relationships for data with multiple structures. I need to track leads. Leads come from multiple sources. Each lead source has its own data structure. I need advice ...
3
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1answer
316 views

What scope(s) is “hasMany” a part of?

I realize, when talking about structures, obviously if you say "post hasMany comments" there are many records about comments relating to each post. What I don't understand is what context these sort ...
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2answers
9k views

Relational Design - Multiple tables into one foreign key column?

Take a table that tracks meat purchases. It has a "meat_id" foreign key column to indicate what type of meat the purchase was. But, the different types of meat are unique in some way (such as USDA ...
0
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1answer
964 views

Entity Relationship Model for linked tables

Certainly a noobish question, but I'll ask it anyway. Perhaps someone else will be thankful. ^^ I am getting warmed up with MySQL and I try to understand the concepts of creating well structured ...
8
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2answers
937 views

How to structure a model to properly and efficiently represent tree-like data on relational databases?

Based on Traversing tree-like data in a relational database using SQL question, I would like to know how the way regularly used to describe tree-like data on relational databases considering physical ...