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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If my understanding of BCNF is correct, how did we know that R1 was not in BCNF?

Given that R(ABCDE) AB->C BC->D CD-> E DE->A Since, B is the only attribute absent on the right-hand side, we would start with B. {B}+ = B . Not a CK. Next, we ...
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Customer table with last order id - violate normalization?

So I'm looking at a customers table that has a relationship with an orders table. There is a trigger in place to set the last_order_id field of the customers table whenever a order it placed. Does ...
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54 views

Should I move repeating foreign keys into separate table?

Idea Users can upload lots of items and send them from processing. From the upload settings I can set a channel to which the uploaded items belong to. Channel is a separate entity. Currently I set ...
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48 views

Lose some FDs in 2nf normalization?

Suppose we have R=(A,B,C,D) and FDs are {B->C, C->D}. The only candidate key is AB, then A and B are prime; C and D are not prime. B->C breaks the 2NF requirements because is a partial dependency. So ...
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Help needed designing a 'Group' concept for students in a class

I've been wracking my brain for a while now trying to figure out how to fit this part of my domain model into the database, but whatever I come up with just feels wrong. I've attached a picture below ...
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47 views

Modeling a product database and dealing with inheritance

So, to get better at designing databases, I'm attempting to model a database system after the AR15 Builder. Here is what I have so far: While it makes sense logically, I'm afraid there may be ...
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62 views

Normalisation to 3NF

I've been learning how to normalise data into a normalisation table and I'm struggling to get my head around this example question. I have this 'clinical record' card: Would anyone able to explain ...
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42 views

Database design for flights, airlines and aviators

I created two tables Airline(airline_id, name) Flight (flight_id, airline_id) - airline_id contains id of airline which perform flight and I want to create third one Aviator But I can not ...
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10 views

Entity Relation in Database Normalization

I'm little confused Entity Relationship in normalization, Normalization will automatically create relation or should we create relation attribute by real world example? Suppose I have these ...
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Likes or votes for posts

I am making a small program where users makes posts or write blogs. On those posts, other users can like or dislike the post as in facebook or upvote or downvote the post as in stackoverflow. I would ...
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113 views

How can I improve this table, and subsequently the performance of the queries I execute on it?

I have inherited this table of POS transaction level data. In my opinion it is terrible. There are 3.5 million rows, which span ~4 years, with a distribution of anywhere between 1 result and 100k ...
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59 views

Relation in 2NF with a transitive dependency?

Tomorrow I have my final exam of Database Design but I have a doubt about the Second Normal Form (2NF). The definition says a relation is in 2NF if no non-prime attribute is partially dependent on a ...
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33 views

Store a revenue based dataset in a relational database

I have several revenue based datasets with below structure: Subject 2012 2013 2014 2015 online marketing 54 50 60 80 website ads 900 850 ...
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48 views

Can this be further normalized?

I have to define a system where we will be storing Image data and which can have an arbitrary number of attributes for the Image added per client. I have designed the following table Image ImageID ...
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138 views

Survey Database - Respondent Table (1NF or 3NF - Pros and Cons)

Building out a Survey ERD ODS layer. Now i'm debating on the design for my Respondent Table. Not sure if its best to have it as 1NF or 3NF. FOr a quick back story I get a survey extract with ...
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189 views

How to remove data redundancy in product table if multiple suppliers are there for same product

I am designing a database where I have different products and suppliers. For example, I have a product, "mobile phone", say an Apple 5S. This will be sold through my website from different suppliers ...
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26 views

Schema Design for multiple many-to-one relationships. of which exactly one should exist

Say I have table A, B, and C. B and C can both be related to multiple A's, but each A should have exactly one of either B or C related to it. Which database design is better: A: a_id, b_id NULL, ...
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55 views

Database design for actions on some entity

I am making a todo list kind of a service. One todo list will have several items , that can be done/deleted/snoozed etc. Users can also add a new item to the list , delete an item etc. I want to ...
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25 views

Create new table values based on partial column value - access

I am trying to remove a ton of unnecessary rows in this table. Currently there are 1.3m of them which are all an individual transaction id - with the country and destination assigned for each which ...
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36 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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184 views

Should I normalize my string arrays, or just keep it a simple string?

I am working on a project involving cards from the Magic: The Gathering game. To be of any use, I must load the basic information about each card into my database, but some of the fields may contain ...
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22 views

What should be the rule for excluding an FD from consideration while doing BCNF or any other Normalization?

Let us consider this example: http://www.mathcs.emory.edu/~cheung/Courses/377/Syllabus/9-NormalForms/examples.html At the first decomposition step, it is using A -> B C D E. On the next step, ...
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What are the prime and non-prime attributes in this relation?

R(HIJKLMNO) L -> MNO HI -> JKLMNO J -> KL K -> H HI is a key. So, H is a prime attribute. But, H is also in non-key part. What are the prime and non-prime attributes in this relation?...
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Design improvement on multiple references

Im having some 'perception' problem, maybe... I got this table linked multiple times with another small table and maybe is more of a personal problem with the way it looks but I feel there might be a ...
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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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1k views

Question regarding 2NF partial key dependency

If the functional depencies are AB-->CD BC-->D IS the relation still in 2NF?,I mean since AB is the key and the 2nd BC,out of which B is part of the key,is the relation still in 2NF??
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Should I normalise this database?

I have two database designs thought of for storing messages(instant messages) between users. It will be a group chat system. I have two table designs in mind. One is this: CREATE TABLE `...
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205 views

Database Design for group chat

I am creating a chat system as a RESTful API. This is what my design looks so far A request can be made to fetch the newest 50 messages that are part of a group id. Even if I do get a list of ...
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204 views

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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129 views

What would be the Candidate key (s) of this relation?

R(ABCDEPG) F={AB->CD, DE->P, C->E, P->C, B->G} To my consideration, the candidate keys are: AB, AG, CD, DE. Am I correct? Why or why not?
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Normalized Table Structure for Logging

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

Normal form definitions

I've had trouble finding a straight definition of normal forms online. I don't want any examples or metaphors, just what each form is defined by in a nice format ! I believe there is more than 4 ...
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Database normalization: Which is the best fit?

I have 3 different types of data set: Notification: start_date end_date notification_type country_id state_id Campaign: start_date end_date user_notification Transaction email ...
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Help with some references [closed]

Kind help if anyone has detailed of what a amstrong database are and how are they useful any current important changes in this field or advice on where I may get info in which forum any link
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64 views

Apply Definition of MVD (multivalued dependency) to Example?

Supposedly this multivalued dependency (MVD) and this functional dependency (FD): {W} ↠ {N,D} and {W} → {N} hold in this table: V W N D ================= | v | w | n | 1 | -------------...
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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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109 views

Entity Relationship Design; The best scenario

TLDR; What would be the best design choice for the scenario below and how would each design react at extremely large data volume? I have experience working with large government database systems ...
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37 views

Is this pattern named and how to normalize it?

I am given a data table : State ( StateId, StateNme, StateCounty1, Statecounty1Seat, StateCounty1Rep, StateCounty2, StateCounty2Seat, StateCounty2Rep, StateCounty3,...... ) ...
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31 views

Struggling to design addresses table for fast querying

I have two tables: addresses and locations. Locations zipcode city county state Addresses line1 line2 city county state zipcode Posts Id Address_id Body All my users are required to provide at ...
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Is database normalization dead? [closed]

I've been brought up old school - where we learned to design the database schema BEFORE the application's business layer (or using OOAD for everything else). I've been pretty good with designing ...
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General Definition of/for Primary Key for Table with Repeated Entries (i.e., not in 1NF)

my first post, my apologies if this does not belong here, please refer me to the/a right site. So I am looking for a general form for a primary key given a table containing non-atomic repeated ...
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77 views

Does the definition of 2NF prohibit _transitive_ dependencies on a partial key or only direct ones?

We know a relation is in 2NF iff it is in 1NF and no non-prime attribute is dependent on a proper subset of the candidate key. But is "dependent" in this definition strict or loose in the following ...
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135 views

How can I prove / disprove If A ↠ BC and A → B then A → C

/ From GATE 2007 IT: Consider the following implications relating to functional and multi valued dependencies given below, which may or may not be correct. A) If A ↠ B and A ↠ C then A → BC B) ...
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How much normalization is too much

I am working on designing a database for a site I am trying to build, I created what I believe to be the best normalization strategy, to limit the size of particular tables, and the number of tables ...
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226 views

Is splitting a CSV column into a separate table(enforcing 1nf) unnecessary complication?

I had very carefully asked the table designer why he had chosen to create CSV columns in multiple tables. The designer's answer was that splitting CSV columns into separate tables was unnecessarily ...
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ER and Precedence Diagrams

I've been having some difficulties creating a "Cruise Ship" database. Basically, what is known to me: Office has information about: Route (final destination/target) Ships Room Room's class (rank) ...
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Is it possible to get rid of so-called 'Spurious Tuples' completely?

Is it possible to get rid of so-called 'Spurious Tuples' completely? For example: In this example from a textbook, there is an original table: I don't see anything wrong with the two projections ...
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What adverse effects does a table have when it's not even in 1nf? [closed]

What adverse effects would a table have if it's not even in 1nf ? I googled and read the article on Wikipedia but I couldn't find exactly why a table should be in 1nf. Also, I couldn't find what ...
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Help Normalize Movie Database

I'm creating a small movie database and was wondering if someone can let me know if I'm in the right path: The main entities are movies, people, jobs, trailers, and photos. My main concern is the ...
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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 ...