Normalization is the process of organizing columns into tables within a relational database in such a way as to minimize redundancy and avoid insertion, update and deletion anomalies.

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Dependency preserving and lossless join decompositions

I have a relation: R = {A, B, C, D, E, F, G, H, I, J} And a set of functional dependencies: G = {AB -> C, A -> DE, B -> F, F -> GH, and D -> IJ} I ended up decomposing into two ...
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Confusion normalizing data to 3NF and transitive dependencies

I am currently in a Database class and have some confusion with normalizing to 3NF. I have one specific issue that was not addressed in class but appears in the book problems. For example I have R ...
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349 views

Normalisation of practise database [closed]

I am a newbie to database design, and I'm a bit confused about how to create a database with minimum redundancy. Suppose I have a table abc with repetition of data in it and no two rows are same. Now ...
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132 views

Relations, dependencies and normal form

I have some issues in understanding about relations and dependencies. I will show two examples and what I want to know: Assume the relation GTX {G,T,X} with the following dependencies: G,X -> T ...
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2k views

Why is a Star Schema more normalized than a 3NF Schema?

According to Oracle's documentation, third normal form schemas "may require less data-transformation than more normalized schemas such as star schemas". I'm confused, I thought 3NF is the most ...
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295 views

Does this database table violate normalization rules?

I’m working with Access 2010. I’m developing a database for a public art program – we paint large scale murals on walls. The database tracks blank walls in the city as potential sites for murals. It ...
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35 views

This database has two foreign keys going to a single field, is it in 3NF?

Firstly, here is a picture of the database diagram generated by SQL Power Architect. I needed to create a user_id pair in order to match friend requests to users, but this has given me two foreign ...
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37 views

Should I create many ID for a same Person/entity in my DB?

In my model, I must store the name of the teacher of some kids and the classroom in which the teachers work, let’s say. All of the hundreds of teachers in the schools have 1 and only 1 classroom, ...
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57 views

I created a DB schema for a project relating to collecting comments for web pages, is relational the way to go and how are my relationships?

I'm curious if relational DB is the way to go, if the current relationships in the diagram make sense, and whether it will bode well for coding.
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49 views

Database Table Design

I would like to ask couple of questions regarding my schema table design. I have the following data coming from an external database where I do not have any control over it. PROD_NO PROD_NAME ...
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51 views

Why wouldn't I put the single preferred option into its own table, instead of having a 'Preferred' column?

In similar spirit to How to implement a 'default' flag that can only be set on a single row I would like to specify that, for any given list of possible names for a business, only one of the ...
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54 views

On modeling pairs with a possibly empty second element

EDIT: I've made the post significantly shorter. I hope it's more digestible now. Consider the following schema: CREATE TABLE X ( x TEXT PRIMARY KEY ); CREATE TABLE Y ( y TEXT PRIMARY ...
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Database design for bookmark system

I am creating a bookmark system where people can save their bookmarks. Each user has its own personal page with bookmarks. A bookmark should have atleast one tag and max five. Each user can create ...
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128 views

To normalize or not to normalizde? (10 fields)

I'm helping someone to design a database and for a specific case I'm not sure. I have 10 fields - this will never change - that will always be filled and used in every query that could be coming up. ...
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2answers
170 views

Design consideration regarding state handling: how to store multiple, variable states for one entity [closed]

First I have to admit that I'm not a database professional neither are my colleagues. For a new project my colleagues and me came to a design question we couldn't really solve easily. And all the ...
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2k views

Normalisation from 1NF to 3NF

I need some guidance on normalisation from 1st Normal Form to 3rd Normal form. I have already set up my database which is working fine but needed to show some normalisation to show that I did do some ...
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503 views

3NF decomposition + database normalization

I am studying for a test and would like to know if I am on the right track to get the following into 3NF with minimal number of keys for R: Given relation R(A,B,C,D,E,F,G) and the functional ...
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440 views

Multiple values in lookup fields

I know newer versions of MS Access allow multiple selections in lookup fields. For example, if I'm collecting information on my students, I can have a field called Race with lookup values that ...
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22 views

Creating UNF for multiple actions

I am creating a database design for manufacture company for my coursework. The database design should be able to do these tasks: Buy items from suppliers. (M - N) Items are used for making products. ...
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Is there any literature on “re-normalisation” of denormalised data?

I'm involved in a project, the core of which might be generously described as "re-normalisation" of denormalised data. (To be fair, the initial implementation took only the first 90% of the time ...
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42 views

How To Manage Random Data Without Repitition?

We have a database design problem of a Learning System. Please can somebody help us ? These are the requirements : A person can register for a module which has "n" number of questions. The person ...
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39 views

Method to Obtain LossLess Join BCNF Decomposition

I have been told a way to obtain loss less join BCNF but I don't know how to calculate candidate keys(also called super key in some cases) and trivial Dependency. I have been given a relation R = ...
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75 views

Is the table in 3NF?

I am creating a relational database - a library management system. I want to show an example where I normalize the data from 2NF to 3NF. My example of 2NF looks like The definition of third normal ...
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163 views

Normalising Customers and Employers with a people table

At what normalisation stage is it recommend to split say Customers and Employees into a people table and then link to the unique attributes of Customers and Employees. I cant seem to find the ...
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175 views

Should database be denormalized if I need an index across multiple tables

I have a catalog of album and song names. The song has a foreign key to the album table. I expect queries like: SELECT * FROM song s JOIN album a ON a.id = s.album_id WHERE LOWER(CONCAT_WS(' ', ...
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Identifying functional dependencies

I'm having trouble understanding the logic in use for identifying functional dependancies. Looking at the sample relation below, I understand fd1 - fd3. But when I look at fd4 and fd5, its logic ...
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Problem with reaching second normal form in a database

I'm currently taking an Databases/Database server course as a part of my education, and for this week we have been assigned a simple project to complete. I'm facing a problem regarding normalization. ...
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216 views

Why is dynamic pivoting not supported? [closed]

TL;DR What is the reason that in 2013 we still can't define a VIEW that displays some pivoted data with a dynamic column set. TL;DR/2 Is pivoting data a denormalization technique? First: Not going ...
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177 views

Can I normalize my experimental data table further?

I am attempting to get a MySQL database to 3NF, but I'm unsure as to how to get there. I'm new to database design, so please correct me if my understanding is incorrect. I have 6 columns: ...
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370 views

Help with normalization - Homework

I'm confusing myself a lot here. I did this before however have never got the hang of it. So I really need help, main issue is 2nf I just get the dependencies completely wrong. So I am practising ...
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795 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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2answers
598 views

To normalize or not to normalize for few distinct values

Assuming in a Postgres database, you have a table called party, which can have less than 5 well-defined party_types such as 'Person' or 'Organization'. Would you store the party_type in the party ...
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Normalization: 'zip code' as a primary key

I've seen frequently that you should not have all address fields (zip, street, city, state, country, etc) in the same table as your user info table (pk_id, name, email... ). This would be in ...
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459 views

Is this table in 3NF?

I have a table person with attributes: id name city state country id is the primary key. Is this table in 3NF? If 1000 people live in same city it seems redundant to store the same data for state, ...
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54 views

SQL Data warehouse and normalization forms

I don't know if it's a simple question but does a data warehouse have different rules when it comes to normalization forms? At the moment I am creating some tables in a data warehouse, and they ...
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60 views

How to design tables such that a person can work for many companies? [closed]

Database design such that a person can work for many companies?
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217 views

What and How is the ID antipattern?

What is the ID antipattern and why / under which circumstances is it considered an antipattern? The id antipattern is having a unique ID column in each table. The ID is generated for each new ...
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932 views

History table design for supertype/subtype

I'm designing an asset management database that tracks IT hardware. I decided to use a supertype/subtype design. I'm at a point where I want to track history of changes for devices. I wanted to use a ...
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286 views

Query regarding normalization of the relations

I am given a case study of Event Management to develop an ER model and based on it its normalization forms and relational schema. Now i have developed my ER Model based on the SRS that i have ...
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116 views

Is it ok to create additional column for helping other column to be a PK?

Let's say a Person can have more than one nickname. He(she) must enter his(her) nicknames alongside with other details: Here is the table columns: User_Id, Nickame, Age Of course, for now there ...
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90 views

Users Characteristics

I'm really battling an issue where I have a Users table that has a growing number of user characteristics (regligion, smoking preferences, etc). The strategy I've used thus far has been to add a ...
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3answers
690 views

Complex query with multiple normalized fields

We have a fairly simple table structure, but with a LOT of fields per table (talking 40+). This data is initially produced in plain-text, user-readable tables, but then it is translated into ...
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27 views

Get one column table when doing localization

I have got only one column for a table when i create two localized tables. Code as bellow. -- Month CREATE TABLE `month` ( `id` INT PRIMARY KEY NOT NULL AUTO_INCREMENT, ); -- Month Localized ...
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108 views

Index optimization on a view using a full outer join

Table structure: Foo FooChild Bar --- -------- --- ID ID ID Date FooID Date ...
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854 views

One field with multiple values?

I know that what I'm asking can't be done or shouldn't be done, but I really don't know how to do it. This is the problem: 2 tables: - Drivers (id_driver, name, etc...) - Trucks (id_truck, model, ...
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60 views

Building dependence between regional data (Street -> City -> PostalCode -> Country)

I'm in the process of designing a database to contain regional data to be used inside a CRM system. So, a user suspects that things like the city or country are automatically filled (or maybe just ...
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2k views

Functional Dependencies and Normal Forms

I'm trying to grasp the concepts of functional dependencies and normal forms, specifically first (1NF), second (2NF), and third (3NF) normal forms. The link here was extremely helpful in deciding the ...
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2answers
325 views

Refactoring/normalization - but almost empty table

I normalized a legacy DB into this structure: But I'm not sure if it is correctly normalized. I don't feel very comfortable with the almost empty filters table. The requirements A group contains ...
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Splitting a column to normalized table

I have a de-normalized table as Original De-Normalized Table id text 23 first,second|third,fourth,fifth|sixth I want to normalize the database to create the following tables Table 1: (Split by ...
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Does this design satisfy 3NF, and can any improvements be made?

Does this design satisfy 3NF, and can any improvements be made? If it does not satisfy 3NF - why? By improvements, I only care if it will seriously affect scalability, efficiency, etc - I'm not ...