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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BCNF when no keys are available

I have a problem understanding a particular case of BCNF. Let's suppose that we have a relation R(B, C, D) with df:{C->D}. Is my relation in BCNF and if yes why??? Is C considered as superkey?
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415 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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Unable to decompose this relation to BCNF

I have a relation R = { A, B, C, D, E, F, G, H, I } And functional dependencies F ={ ABC -> DE E -> C AB -> F C -> G F -> H H -> IJ F -> B } I am able to do simple BCNF ...
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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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247 views

Does my design adhere to 3NF?

I created this schema with OpenOffice. Does this design adhere to 3NF ? (A relationship link between Equipment and Supplier_Equipment , Customer and Membership should be created but OpenOffice ...
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Simple scenario needs to go from Unnormalized Data to 3NF - Review Please

NOTE: The Question has been updated. View Edit Revisions to view original question. The scenario. An animal charity that at the moment, track their establishment's costs via a spreadsheet like so: ...
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476 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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3k views

Best practices for history/temporal tables?

Suppose I have an object, with certain fields which I want to track history, and certain fields which I do not want to track history. From a normalization perspective, is the following schema alright: ...
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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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Why is this relation in 3NF?

I have a relation: R4 = {{T,U,V}, {T → U, U → T, T → V}} I know from looking at the answer key that this relation is in BCNF. I'm going through the process of rigorously determining what normal ...
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193 views

Database functional dependency BCNF help

I understand most of BCNF and have been able to complete numerous problems with it, I'm just having trouble applying it to the following situation: R(A,B,C,D,E) FDs: { A->D; BE->A; CD->E } Here's ...
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How to normalize data based only on the repetitions

Given a non-normalized data table, is there a good a strategy to attempt to normalize based on repeated data? Assume we have no information about the significance of the columns. In a small example ...
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322 views

Same product name with different price in different states

Consider the price of products in the table differs in each state. If the price varies in district I also have to mention it. How can I do this for more than 5 states? product Name Price ...
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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 ...
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1answer
107 views

Expanding contractions/number ranges into separate records [closed]

I am planning the migration of a directory of image files plus a FileMaker-database containing the corresponding metadata into an Imagic IMS database (formerly known as ImageAccess). The vendor ...
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3answers
234 views

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 ...
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621 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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301 views

Are these database tables normalized?

I am developing a webapp for an institute and I designed these tables: Are these tables normalized?
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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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157 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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686 views

Separate or Combine 2 Tables with Similar Attributes?

I have two kind of users in my business system: Customer and Employee. Both user have Username, Password, Fullname, Phone Number, Email, and other similar attributes. I have a difficulty to ...
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852 views

Normalized Table Structure for Logging

How can I normalize a table that has four columns for logging the latest activity for a single record: Created On Created By Modified On Modified By We have dozens of tables, all with these 4 ...
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101 views

Difficulty in finding Candidate Keys

I have an homework which should be submitted tomorrow I normaly know normalization concepts but in some questions I have difficulty. How should i normalize this to BCNF? Can you show the steps please? ...
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748 views

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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I need help to migrate denormalized table content to normalized form- MS Access

I have a staff database where we are storing information in Normalized form. There are 3 entity tables and 2 mapping tables connecting these with m-n relationships However, for ease of collecting ...
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473 views

What is best practice to organize / normalize database tables?

I manage group that uses a database that is about 12 years old. There are more than 200 tables / views that have been created by various people over the years, many of them no longer with us. Most ...
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Stroring a type of an entry

There is a table estate with numeric fields districtru and districthe (for a name of a district in Russian and Hebrew), which refer to primary keys of the table districts. The districts table has the ...
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201 views

Most efficient way to structure segmented data

I am faced with a set of data which I am currently unsure on how to store efficiently. The data in question relates to a calendar which stores information on two different categories of event which ...
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Does my table violate normalization rules?

I am developing an emulator for a game. My item table looks like this: -- ---------------------------- -- Table structure for `items` -- ---------------------------- DROP TABLE IF EXISTS `items`; ...
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How to change type from one owner to two different types of owners

I currently have (tables changed): User UserID uniqueidentifier, CompanyID uniqueidentifier, (for future reference) .. more unrelated fields (PK: UserID) UserRating UserID uniqueidentifier, ...
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147 views

Database Design - When to use “attributes” rather than additional columns

I'm wrestling with a schema design issue. I'm attempting to determine when I should add another column instead of making it an "attribute". Rather than adding a numerous columns to a table, I ...
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Database Design for Questions and Answers

I'm building a website that will host a variety of questionnaires. Each questionnaire has a different number of questions and each question has a different number of answers. I have attempted to ...
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204 views

Mobile Phone & Tariffs

I have designed database tables of Mobile Phones & Tariffs. It should support multiple mobile networks, sale type and the related affiliate. Points (for operators) are vary depending on the ...
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387 views

Normalization: Should common columns of two tables be pulled out into a third table?

Should I further normalize my current design to eliminate redundancies? I have the following tables: empl: standard user table empl_cat: employee "category" empl_admin_cat: administrative ...
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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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Database normalization: Describing trait - foreign key to table, or varchar field with value?

My colleagues and I are having a discussion about the normalization of descriptive traits in the database, such as "status" or "type". Let's call the central table of the discussion "Order". In my ...
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Does this normalized model for artist music records make sense?

I want to make a database about one artist's music records... CD, Vinyl, Cassette, 8 Track, Singles, Ep, Lp, etc... I believe I have a good normalized model that will achieve my needs, however before ...
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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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Writing to a DKNF database, but reading from a de-normalized table for performance?

Would the following approach be reasonable? The Goal: queries have to be relatively fast, but without the hassles incurred by writing to a de-normalized database. The Context: A database for ...
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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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148 views

Reporting Table Design

I'm writing a system that allows users to store values against each week in October and November and each day in December - starting from the first Monday. I'm holding the raw data entered by the ...
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481 views

shoud we normalize user profile table with fields like interests,musics,videos,sports, etc?

I've read in an article about social networking database schema and saw that they've used varchar for those columns that I mentioned in the question title. It's not normalized! Isn't it better to have ...
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is id and phone number enough to uniquely identify a row in phone numbers

Was designing a table a customer_phone_numbers table a while back, which only purpose was to allow us to store as many phone numbers as a user wanted to have on file. I originally came to the ...
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803 views

Database Schema for an address book with different mailing lists

I'm helping a friend out with taking an old excel, single-page database which contains around 12 different columns that store information about: person first+last name email(s) current address ...
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263 views

Migrating and normalizing data

We are rewriting a large Django application which uses a MySQL database, and the database schema needs to undergo major modifications. We're also porting the app to use PostgreSQL, for a couple of ...
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563 views

Good reason to denormalize?

I have a database with about 40-50 tables. All but 5 are part of a giant hierarchy of 1:M relationships that all point back to one solitary parent (call it "Project"). Each table is joined to its ...
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Normalization and Breaking down tables for InnoDB

I'm designing a web application, something small but deals with lots of read and inserts. Let's say 60% read and 40% writes. My storage engine is InnoDB on MySQL. I have a table called User which has ...
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3answers
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Optimisation Newbie: How much of a 'sin' is redundancy?

I've been developing for a while, but never really had to deal with DB/scaling issues before. That's suddenly changed and I've found myself in the deep end. I have 2 SQL tables, as such: VOTES ...
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How far should you go with normalization?

I have a decent amount of data in a database. I have well formed tables and good relationships between them with some redundancy in my data. But how far should I go with normalization? Are there ...
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2NF decomposition + database normalization

If anyone knows about 2NF I'd greatly appreciate if you could tell me if my understanding of it correct my book does not even mention it (except to say is of "historical significance") and I haven't ...