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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Challenge: Build MySQL table that's not in first normal form [closed]
I have read numerous books and articles about database design and SQL in which it is said that a database should be in first normal form (1NF). (Some then go on to describe situations in which it may ...
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1answer
73 views
Is this table in 3NF?
I have a table person with attributes:
id
name
city
state
country
id is the primary key. Is this table in 3NF? If 1000 people live in same city it seems redundant to store the same data for state, ...
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1answer
63 views
Functional Dependencies and Normal Forms
I'm trying to grasp the concepts of functional dependencies and normal forms, specifically first (1NF), second (2NF), and third (3NF) normal forms. The link here was extremely helpful in deciding the ...
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2answers
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Column partially determining accepted values of another column, should be somehow normalized?
I have a table that describes a set of properties (yes it's metadata, in this case there's a valid reason to have it in the database); among other things I tell the type of the data that can be ...
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1answer
39 views
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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1answer
79 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 ...
3
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2answers
60 views
Normalization/normal forms - May a field describe an other field?
Like this:
CREATE TABLE persons(
id serial8 NOT NULL PRIMARY KEY,
name varchar,
-- A lot of other fields
date_of_birth timestamp with time zone,
date_of_birth_precision ...
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2answers
216 views
Refactoring/normalization - but almost empty table
I normalized a legacy DB into this structure:
But I'm not sure if it is correctly normalized. I don't feel very comfortable with the almost empty filters table.
The requirements
A group contains ...
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0answers
49 views
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 ...
7
votes
2answers
145 views
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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1answer
84 views
Approach to Analyzing Database Requirements
When presented with requirements for a database driven system, I always find it useful to imagine a world with no computers, where data records were kept in filing cabinets and data was collected by ...
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3answers
240 views
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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3answers
112 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 ...
1
vote
3answers
152 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:
...
2
votes
1answer
322 views
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 ...
2
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2answers
123 views
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 ...
0
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1answer
80 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 ...
0
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1answer
85 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 ...
2
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2answers
77 views
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
...
3
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3answers
469 views
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 ...
1
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2answers
148 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 ...
0
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2answers
105 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??
2
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1answer
102 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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2answers
129 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 ...
2
votes
1answer
715 views
Decomposition of a relation to 2NF then to 3NF
I'm currently studying for my exams and the trouble I am having is how to decompose a relation R with given functional dependencies into 2NF then 3NF.
For example for the following R and functional ...
3
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1answer
230 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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0answers
65 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?
...
2
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1answer
173 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 ...
3
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1answer
100 views
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 ...
2
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1answer
230 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 ...
