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Questions tagged [normalization]

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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Can the Chase test algorithm only modify attributes on the right side of a functional dependency?

I'm attempting to apply the Chase Algorithm to determine if a decomposition is a lossless join decomposition. Functional Dependencies = {A → C, B → D, C → D, DE → C, CE → A} Here is my initial ...
student_1123's user avatar
4 votes
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Superkeys of this relation

I am trying to find the superkeys of this relation, but I am having troubles finding out how many superkeys there are and exactly what they are. I figured out that the candidate keys were {A},{B},{C},{...
Jason's user avatar
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3 votes
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Best practices for heavily coded data in a relational database and lookup tables

I'm working on converting a legacy system into a more modern web application and I keep finding myself tripping over normalizing the data. The dataset is quite large; about 30 tables with around 15 ...
Kenny Read's user avatar
3 votes
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Third Normal Form (3NF) Decomposition Scenario

I am trying to understand what are the steps to check if a decomposition of table is in 3NF. There is a specific exercise I'm trying to solve with no success. Given that R={A1,A2,A3,A4} and F={A1→...
Roey Waitsman's user avatar
3 votes
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How do you perform the chase test?

Trying to follow the chase algorithm as I understand it, If two rows agree in the left side of a functional dependency (FD for brevity), make their right sides agree too. Always replace a ...
SS''s user avatar
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3 votes
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Optimality of Columns vs. Complementary Table in MySQL

I'm starting work on a project where I'll have a table of entries as well as a table of descriptors. The entries will be updated infrequently, if ever, and the descriptors table will be largely ...
Cameron Sumpter's user avatar
3 votes
0 answers
676 views

Why is dynamic pivoting not supported?

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 ...
Martin's user avatar
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For selling items in a game, should the shop and item tables be merged?

I'm developing a game that uses a Postgres database. In the game players can have many different items, and each player can have multiples of an item (example: 200 apples). My item table currently ...
Ryan Peschel's user avatar
2 votes
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51 views

One-to-One? or One-to-Zero-or-One?

Scenario: I am being asked to create an HR training tracker for employees of a business. in this database I am using two tables: EMPLOYEE(EMPLID, LastName, FirstName, PrimaryEmail) with EMPLID as the ...
Nathan Willett's user avatar
2 votes
0 answers
51 views

How to enforce NOT NULL for sixth normal form in PostgreSQL

I have a table person which I am planing to normalize to the sixth normal form. The table has attributes username, email, and phone. The reason I want to go to the sixth normal form is keeping the ...
Eerik Sven Puudist's user avatar
2 votes
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How to handle / model "cost of provided spare parts per PO line item" where one spare qty is divided between multiple line items? / Postgres 11

Problem My objective is to help improve the data modeling / handling of my company’s present cost-of-goods [‘COGS’] calculation. Everything in the current Postgres 11 table structure is pretty ...
Mister October's user avatar
2 votes
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101 views

Design issue in transitive dependencies between tables

This is a made-up scenario, but I imagine that it can be of general interest, so I'll post it here. Imagine the following business rule: A course has a grade scale that determines what grades a ...
Lennart - Slava Ukraini's user avatar
2 votes
0 answers
86 views

How to handle normalizing the concept of a grid, and also plan for data versioning?

I have inherited a database that has a normalized structure, except for its data tables which are aggressively denormalized. Our system mostly renders grids into a browser, and the previous developer ...
James's user avatar
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2 votes
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59 views

Setting up a Grand Jury relational database structure

I'm designing a database to store information about a grand jury. I'm wondering if my tables are normalized, and if they structure makes sense. A report is sent in for review by grand jury. Then a ...
Brandon Finley's user avatar
2 votes
1 answer
87 views

Assessing the normal form for a relation with a multi-valued attribute

Assume that you have designed the following schema of relations: COURSES (CID, CNAME) STUDENTS(SID, SNAME, FAV_CIDS) However, you can not have a relation with set valued attributes (Did not really ...
conthoughisck8er's user avatar
2 votes
2 answers
57 views

Schema For "Other - Add Comment"

Many user forms contain an option for "Other - Add Comment" where the user can provide an item not found in the given list. In other words, the developer sets the list of items. The user must either ...
Steven's user avatar
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How to design normalized relations to store “global/generic” data?

Context I was designing a relational database model to store data about a company and its production facilities. I had a facility relation and many other relations referencing it, most of the time ...
soliz's user avatar
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Understanding multivalued dependencies

This is my first time studying multivalued dependencies and there is a question that was posted by my lecturer as a class exercise. I have an answer, but I'm not 100% sure it was right. Please let me ...
Nick's user avatar
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2 votes
0 answers
324 views

Sparse boolean tags: many columns or multiple tables?

I'm pretty new to database design. I'm storing records which are tagged with some (few) of a (large) number of possible tags (much like StackExchange questions). At the moment I have a single table ...
Samizdis's user avatar
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2 votes
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82 views

Array of integers vs through-table

In a scenario where multiple short strings of text in table2 are to be associated with various rows in table1, is it better to use: A through-table with 3 columns: id, table1_id, table2_id? This ...
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Normalization vs denormalization for these kind of data?

I'm using Firebase realtime database (NoSQL), And trying to figure out the best database design for my data. My data is primarily about discounts, each affiliator introduces a number of discount ...
Rafael Adel's user avatar
2 votes
1 answer
77 views

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 ...
Snowtek TV's user avatar
2 votes
0 answers
72 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 ...
Justin Jansen's user avatar
2 votes
0 answers
191 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 ...
Vaelyr's user avatar
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2 votes
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168 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. ...
remonray's user avatar
2 votes
0 answers
59 views

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 ...
Paul A. Hoadley's user avatar
2 votes
0 answers
59 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 ...
monica's user avatar
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2 votes
0 answers
419 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 ...
lala_12's user avatar
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2 votes
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136 views

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. ...
Patrick Jørgensen's user avatar
2 votes
0 answers
595 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 ...
Kyle93's user avatar
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1 vote
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How to design a relational database schema for music recordings?

I would like to design a simple relational database schema for music recordings and normalize it to the ultimate normal form with respect to the projection and join relational operators, which is ...
Géry Ogam's user avatar
1 vote
0 answers
468 views

BCNF decomposition which generates redundant relations (as for 3NF)

Sometimes the 3NF synthesis decomposition algorithm (such as the one described here p.4) generates redundant relations, where all attributes of some R_i already appear in another R_j. The algorithm is ...
Tran P.'s user avatar
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1 vote
0 answers
685 views

Can there exist Tables with no Non-Prime Attributes? If so, are they always normalised to 3NF?

Can there exist a table with no non-prime attributes? Here is an example of a table which I believe has no non-prime attributes: I came to this conclusion because the list of attributes in the ...
Pixelchai's user avatar
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1 vote
0 answers
167 views

SKU and Price on product that have multiple attributes

Currently, my Inventory system is writing products data like this: T-Shirt Gildan -> blue, L, short -> stock: 140 -> price: $40 T-Shirt Gildan -> blue, XL, short -> stock: 0 -> price: $45 T-Shirt ...
Engkus Kusnadi's user avatar
1 vote
1 answer
1k views

Finding all possible minimal covers

I have a relation schema R = {A, B, C} and the following functional dependencies: A → B A → C B → A B → C C → A C → B How many different minimal covers can I derive from this relation schema? I have ...
BlackPearl's user avatar
1 vote
0 answers
291 views

verifying non-additive join decomposition

I am reading a DMBA book and have come across non-additive (lossless) join property. The algorithm for decomposition into multiple tables is borderline useless for practical work, so I am frequently ...
sanjihan's user avatar
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1 vote
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1k views

Is a relation with two attributes always in Boyce-Codd Normal Form (BCNF)?

I went through some tutorials on BCNF and got that a relation with two attributes is always in BCNF. My question What if a relation with two attributes has no prime or non-prime attributes? That is, ...
PS Nayak's user avatar
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1 vote
0 answers
528 views

How to check if functional dependencies are preserved?

I have the following functional dependencies for the schema R=(a,b,c,d,e,g): {b→c, dg→ce, bc→dg, e→a, g→bd}. I want to decompose R into two schema's: R1=(a,b,c,e) and R2=(b,d,g) and make sure the ...
Yos's user avatar
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1 vote
0 answers
80 views

Normalizing a relation schema with 'abstract' attribute names

I'm a student currently attending a database design course and I'm having some issues normalizing 'abstract' attribute relation schemas from 1NF all the way to 3NF. When we used examples with '...
Rodrigo Ehlers's user avatar
1 vote
1 answer
79 views

Now to normalize table when position in group uniquely identifies entity

I need to model charts such as the one displayed below... ... and came up with the following: For the sample chart I originally showed.. charts.name is "Custom transactions", charts.y_legend is "...
user1032531's user avatar
1 vote
0 answers
167 views

Protocol for Converting External Unnormalized Data to Normalized Tables

I'm working through the fundamentals of bringing data from Excel (or any single unnormalized form table model) to SQL (MySQL or SQLite). These are the steps I've extrapolated from reading: Import ...
J.P.M.'s user avatar
  • 111
1 vote
2 answers
658 views

Database Design for Maintaining Supplier Invoice

I am not sure whether it is right to ask such question here. However, It comes to my mind this would be the best place to start. My needs are quite simple. As a distributor, I want to maintain all ...
theJohn's user avatar
  • 11
1 vote
1 answer
28 views

Implementing 2 keys table in sql

Considering this table > TRIP Table : ( Code [pk] , Origin , Destination , Distance ) how to make (Origin , Destination) attributes has the constraint of composite key "can repeat if one of them is ...
user112356's user avatar
1 vote
0 answers
489 views

How to further optimize database schema about IT asset/inventory management

I am currently working on a project to create an IT Asset/Inventory Management system. My approach was to take their mess of spreadsheets and convert it to a relational database. It will be used to ...
Evan Bechtol's user avatar
1 vote
0 answers
59 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 ...
finsalscollons's user avatar
1 vote
0 answers
227 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 ...
Francis's user avatar
  • 11
1 vote
0 answers
242 views

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 ...
Pete B.'s user avatar
  • 111
1 vote
0 answers
74 views

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 ...
harveyslash's user avatar
1 vote
0 answers
100 views

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 ...
harveyslash's user avatar
1 vote
0 answers
34 views

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 ...
Mirrana's user avatar
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