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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Database Design (how to handle subclass & superclass)

I'm wondering what is the best approach to this type of problem (I'm a highschooler so don't have practical knowledge on the subject): Let's say I want to store information about employees at a zoo. ...
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1answer
41 views

How would i create a report involving multiple many to many relationships

Lets say table A has a many to many relationship with table B, and table B has a many to many relationship with C. Two junction tables are created for AB and BC to form the many to many relationships. ...
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31 views

Final Unique Index for Person and Companies?

I am creating a persons schema where the the person table must be very simple because it will be father of other tables that completes it, but a person can be fisical or legal, so I wont put any ...
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208 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(' ', album....
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30 views

Normalization problem

Let's suppose a database table such as this: Table = {Competition, Sport, Game, Player, Score} And we have these functional dependencies: Competition + Game + Player -> Score Game -> Sport Player ...
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188 views

Modeling a database for Video Game related information with multiple many-to-many relationships

Scenario I am relatively new to database design, and I decided to make my own hypothetical database for practice. However I am having trouble modeling and normalizing it, as I esteem that there are ...
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1answer
219 views

Reporting on a normalized Key-Value pivot

ERD & SQL Fiddle provided. We're trying to design a reporting tool for our stakeholders around a normalized Key-Value Pair model. We've tried to find a solution using Pivot Tables but can't seem ...
3
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1answer
337 views

Storing created/retired dates for a large amount of different entities

In the db I'm working on now almost every entity has these 4 columns: CreatedDate CreatedBy RetiredDate RetiredBy Usually this is used for logging purposes, and for some of the entities the ...
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1answer
61 views

What is meant by “minimal” key?

I'm going though some past papers for my database exam and it asks: Specify all minimal keys for R R(A,B,C,D,E) A → B CD → E E → A B → D I am unsure what is meant by minimal key, I've tried ...
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1answer
24 views

Checking for BCNF in a relational database through FDs?

Okay so I know that for BCNF, when listing all non-trivial FD's that everything to the left has to be a candidate key. So I have this relation: Person(Id, TFN, Name, Phone) Where Id and TFN(Like ...
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1answer
35 views

Decomposition and lossless joins

If someone walk me though the following questions I'd be very grateful. Consider a relation R(A, B, C, D, E) with the following functional dependencies: A, B → C D, E → C B → D i) ...
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1answer
22 views

Decompose this relation into BCNF

Today, I'm reading about BCNF decomposition algorithm. It says that: BCNF Decomposition Algorithm Input: a relation R0 with a set of functional dependencies S0 Output: a decomposition of ...
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1answer
31 views

problem transforming table to First normal form

I have table named Agent. It has attribute named agent_status. It's value can be on or off. I want to conform this table to first normal form. Do i have to create different table for this attribute?
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Online text based game design - Am I linking the databases correctly?

I'm trying to recreate an old game that I used to play that went offline quite some time ago. I'm doing this as a hobby project for myself with the hope that maybe a few hundred people might enjoy it ...
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5answers
15k views

What is Atomic Relation in First Normal Form

I have read the definition of 1NF which is, "If each attribute of relation is atomic". Please tell me what is Atomic.
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3answers
731 views

Blockchain (Bitcoin) as a database?

I was reading this BBC News article and the following excerpt, caught my attention. It sounds like Always On Availability Groups or High Availability Mirroring, maybe with security automatically ...
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1answer
26 views

Determining if a relation is in third normal form 3NF

I have a ralation R(A,B,C) with the functional dependencies as follows A->B A->C B->C with A being the candidate key, is this relation in 3NF? well because by analyzing the first two ...
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2answers
47 views

DB Normalization ends up with 2 similar tables

I've been googling for a long time now, reading lots of Normalization Tutorials, but haven't found an answer to my question.... The problem (in this question) is when I have something like a trip, ...
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Normalizing a table with a field that generally uniquely identifies a row, but is sometimes null

forgive me if this has been asked and answered before. I'm roughing out a schema for an inventory management system, to be implemented in PostgreSQL. All of our products and services have a sku. ...
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1answer
31 views

checking the normal form of the current table

I have a schema R1(A,B,C,D) with the following functional dependencies A->B CD->B A->CD CD->A I need to figure out which is the highest normal form in which the following table ...
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22 views

Third Normal Form (3NF) Decomposition

I want know how the decomposition perform in 3NF I have a relation dept_adviser(s_id, i_id, dept_name) Dependency are in relation I_id---›dept_name S_id, dept_name---›i_id After decomposition ...
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2answers
66 views

Dependency preserving decomposition

Let be the following relational scheme: F={AB → C; AC → B; AD → E; B → D; BC → A;E → G} Is the following decomposition without loss of dependency? R¹=(A,B),R²=(B,C),R³=(A,B,D,E),R⁴...
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28 views

What normal forms are these two relations in?

I have a set of relations {A, X, Y, Z}: Given that the functional dependencies: AX→Y, AX→Z, Y→A, Z→X, I would think that this relation would be in the normal form 1NF, because there is a partial ...
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1answer
21 views

How do you normalize a table that is indirectly dependent on a has-many relationship?

I currently have the following database design: Product: contains various description attributes Belongs to many ProductSets ProductSet: Has many Products Belongs to many Stores Store: Has ...
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48 views

Looking for suggestions to model a database of Electrical Components

We have a database of electrical components and I am trying to make sure I have a good design. I am not a database designer (my comfort zone is designing with these hardware components), so I am ...
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62 views

Is this table in third normal form?

I have a table L(A, B, C). Functional dependencies are: A->B, A->C, B->A, B->C. Is this table in 3nf? My thoughts: A and B are keys of this table. Table is in 3nf if there are no transitive ...
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281 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 can't seem to find the ...
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30 views

Is this database in 1NF, 2NF and 3NF?

I'm doing a software development course and I have to normalise my tables as part of it. Can anyone double check that my data is normalised correctly? The database is for a gym. It has these tables ...
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15 views

Algorithm of decomposition in Boyce-Codd Normal Form

I have to give the keys of the following relation, say if they are 1,2 or 3NF and give a BCNF decomposition. Yet I think I misunderstand the difference between 2NF and 3NF: R(A,B,C,D,E) with F¹={A→B;...
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1answer
31 views

does merging tables always increases performance?

Consider we have data from visitors in a web site. And you are trying to create a database design for data mining. There are some common fields which users have such as browser,ip, etc... . But there ...
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1answer
60 views

How to decompose this relation into 3NF relations?

Today I read about the 3NF decomposition algorithm. It said: Find a minimal basis of F, say G For each FD X → A in G, use {X, A} as the schema of one of the relations in the decomposition ...
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1answer
40 views

I'm a beginner, studying Data modelling as part of my course. I'm having trouble understanding Normalisation. How can i improve?

It was difficult to frame the title given the word limit, so apologies for that. Currently I'm studying DBA and Data modelling as a part of my ICT Apprenticeship course in a Web Development team. I'm ...
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1answer
82 views

Minimal 3NF normalization issues

I'm trying to learn how to normalize to 3NF but the example that my teacher gave us doesn't really help. The algorithm I always used is this one: Find a canonical cover F_c for F For each FD X->Y ...
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1answer
98 views

Lost (and found?) on 4NF

I'm so extremely lost on 4NF it's not even funny. I've been reading on it for literally days and, except for about 15 minutes ago, I wasn't sure that I had even broken the surface. I think I might ...
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64 views

Better deffining a parent-child relationship on a table

Our team is developing a new system and it has a Warehouse table that must have a hierarchical relationship between entries since a customer can have 1st, 2nd, 3rd and Nth degree warehouses. We first ...
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Is this a violation of Normal Form?

Assume a cash register system where some users have access to a cash drawer, while others do not (they can only close by some kind of card payment). Keep in mind that a user who closes a check a one ...
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First Normal Form, why is it good and how does it reduce redundancy

I asked a similar question on SO and was advised to ask the type of question here. This is for a course on relational databases. A sample problem asks "how come every table in a relational database ...
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1answer
20 views

Are there any schema design changes that can take a design from 4NF into a different 4NF design?

My thought/contention is that once a database schema is in 4NF it by definition can only be changed into something less than 4NF (Denormalisation, 3NF etc) and that there is no alternative 4NF design ...
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1answer
43 views

What are changes made to a database schema that is already in 4NF that would break applications?

For this question I consider applications select and use columns by name (so I am excluding use of select * as a breaking change). Asked in a different way, is it the case that once a Database schema ...
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1answer
27 views

Applying second and third Normal Form

Let be a relation R(NameFile, Size, Directory, DateCreation,HourCreation,Login,AutAccess,DateAccess,TypeAcces F={NF,D→S; NF, D →DC; NF, D→HC; L,NF,D→A; L,NF,D,DA,HA→TA; } Part of ...
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What problems are solved by splitting street addresses into individual columns?

We have a team who designs the tables and relations for software developers. In our organization, they are pretty strict about enforcing 3NF normalization - which to be honest, I agree with given the ...
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1answer
35 views

How to put the below data in 3NF?

I need to put the data from the diagram in 3NF (third normal form)
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49 views

Why is this not in 2NF and 3NF form? [closed]

R = {A, B, C, D, E, F} Dependencies: {A} -> {C,F} {C} -> {D} {B} -> {E} a. this relation is in 1st normal form (NF). Explain why it is not in 2nd NF and not in 3rd NF. b. make the ...
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65 views

contradiction of 3rd normal form on address table

I have an Address table and its columns are address_id, address_1, address_2, city, state, country, pin code .Its primary key is address_id . According to 3rd normal form no non-key attribute should ...
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1answer
25 views

Relation Between Normalizations [duplicate]

say we have a fixed table T. Is there a unique normalized version of T, i.e., does the/a correct normalization, say up to 3NF produce a unique table up to some equivalence? Basically, I am trying to ...
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Clustered index on last_update_at timestamp

I have a Votes table , which can be considered a wrapper. I have a sub_items table, which holds one votable item. One Vote has many sub_items. On sub_item is owned by only one Vote. I have a ...
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46 views

How would you normalize a database that has multiple products to a single transaction ID?

How would you normalize this? I can't find a way to keep multiple products under a single SalesID
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What is the most efficient way to represent this relationship?

In the database a user can follow many different users. I'm looking for an efficient way to represent this. In the image above you can see my initial idea. This works however results in duplicated ...
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1answer
42 views

What kind of table structure to use to display product, testing, and test results?

I am creating a database, but I am a beginner. We test several different kinds of paint, with specific test methods, and I would like to document all of the results. So for an example, I would test ...
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How to improve on this database design

I have different 'modules' . Currently , they are: Votes Chats To-do lists I am using mysql and long polling to get updates about these modules in near real time. I have also have a table called ...