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 ...
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237 views

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},{...
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109 views

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→...
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4k views

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 ...
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82 views

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 ...
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1k 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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354 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 ...
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53 views

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 ...
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75 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 ...
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40 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 ...
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55 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 ...
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1answer
67 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 ...
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2answers
51 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 ...
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108 views

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 ...
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159 views

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 ...
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227 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 ...
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56 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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472 views

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 ...
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1answer
61 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 ...
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63 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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186 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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146 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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58 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 ...
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53 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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351 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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118 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. ...
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586 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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263 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 ...
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48 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 ...
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1answer
154 views

Database Model for Various Type of Sensors

I am planning to build a database that will store sensor value for various type of sensors in a factory building. Is there any best practice on how to do this? - Option 1 : should I integrate all ...
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128 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 ...
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867 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, ...
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269 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 ...
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69 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 '...
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1answer
70 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 "...
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80 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 ...
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1answer
399 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 ...
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1answer
25 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 ...
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296 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 ...
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56 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

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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234 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 ...
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68 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 ...
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95 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 ...
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30 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 ...
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35 views

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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62 views

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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72 views

is this normalization correct

is this normalization correct for UNF to 3NF
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53 views

PostgreSQL: labels vs columns

I have a data structure similar to this: date foo bar baz boo ---------------------------------------- 2015-11-18 1 null 2.5 81.0 2015-11-19 1 78.4 12.8 ...
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DATE - Normalization, a multiple ranged query, multiple inserts and multiple update

I have a booking system, airbnb style. TABLES -> prices, house, available_date A house has available days and not available days, but sometimes the days have different prices. A weekend is more ...