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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Users_With_Messages Table normal form

I have the following tables in my database: Above these tables (not pictured) is a Users table where the SendingUserId and ReceivingUserId are keyed onto (they are foreign keys). Are these tables ...
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42 views

Does this break normalization?

I have an order table, and in the order table I have a contact_id. Now, each contact is linked to an account. For my order table, should I have both contact_id and account_id? If I wanted to say, ...
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39 views

Normalization of irregular relations?

I have two tables in MySQL: The orders table CREATE TABLE `orders` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `transaction_id` varchar(20) COLLATE utf8_unicode_ci DEFAULT NULL, `task_id` ...
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131 views

Decomposing table into BCNF that preserves dependencies

I have a relation like R(A,B,C) and dependencies like A->B , B->C , A->C I think the relation is in 2NF as candidate key is A. AFAIK when there is only one candidate key then the ...
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2answers
342 views

When normalizing a relational database, should multiple “type” tables be combined into one?

Before making substantial changes to the content, functionality and design of my website (I'll be refactoring everything, almost a complete rewrite), I'm setting up a new PostgreSQL database to hold ...
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92 views

Is two unrelated tables with foreign keys to a third table breaking first normal form?

I was wondering if this breaks first normal form. AddressTable Id - PK Street City State BusinessTable Id - PK BusinessName AddressId - FK PersonTable Id ...
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1answer
136 views

Confusion normalizing data to 3NF and transitive dependencies

I am currently in a Database class and have some confusion with normalizing to 3NF. I have one specific issue that was not addressed in class but appears in the book problems. For example I have R ...
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1answer
367 views

Airport Database Design guidance required

I am trying to make a generic database for airport management and DBMS would be oracle 11g xe. Since, i am amateur and still learning so i have tried to kept the problem statement simple with limited ...
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23 views

loading k:v pairs from DB into JS Object

I'm creating a single player web RPG. I'm debating the following method of storing/retrieving quest items per player id: In userstats table, have a quest_items column of type mediumtext, where I ...
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1answer
115 views

Rules for Decomposition to 2 NF

I am struggling with the concept of 2NF form. Lets say I have a set of functional dependencies for R1(A,B,C,D,E,H,M,K) Where : B -> M,C AB -> D DH -> E H -> K A -> H Whenever I ...
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3k views

Airline reservation system [closed]

I'm making a simple airline reservation system. But I'm not sure about the design decisions I made. Concretely, I'm trying to implement following constraints: each Aircraft can have one or more ...
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48 views

Normalization to BCNF help needed

I have a table with 5 columns as A, B, C, D, and E. The functional dependencies are: AB -> C,D,E BCD -> A BCE -> A,D BD -> E I think AB is the candidate key. I can't find any other candidates. ...
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157 views

Database normalization tables

I am creating a database for a very basic website. I have created the tables and put what I thought might be the correct schema, however I am having doubts about it as well as a couple problems. All ...
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23 views

Difference in the workload related to data-amount and search option

A couple of days ago I was asked why it is necessary to use the first normal form also for separation of names. We have a table which stores private customers (Name+Surname;Information) and business ...
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3answers
424 views

Does 3NF require 2NF?

I am a bit confused with the definition of 3NF. According to Wikipedia: The third normal form (3NF) is a normal form used in database normalization. 3NF was originally defined by E.F. Codd in ...
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1answer
53 views

Decomposing into 2NF

I'm currently studying normalization. I know how to normalize the data for given unnormalized list. But I found this question in our past papers. I don't know how to answer to it. Q. Decompose ...
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1answer
74 views

UK Addresses in 3NF

I am in the process of creating a UK only database which holds information for various sets of people i.e. Staff, Clients etc. The tables for each of these sets of people have an Address, City and ...
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1answer
145 views

Is this design in 3NF? Why to choose another design not in 3NF

Having the following entities: Objects, Parts, Subparts and Items, and given the following design restrictions: A Part belongs to one and only one Object. A Subpart belongs to one and only one Part. ...
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138 views

How to convert this relation to 2NF?

In my Entity Relationship Diagram, an entity type TEACHER had a relationship of TEACH with another entity type called CLASS. CLASS was a week entity type of TEACHER,so when mapping to a Relational ...
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1answer
96 views

Given the functional dependencies of a relation is there more then one way to normalize it?

I"m studying normalization and have been reading through descriptions and examples online. One Concept that isn't clear to me is if the process can be automated at any point. I understand that a ...
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1answer
84 views

Database Over Normalized [closed]

How can you tell when a database is over normalized? Example: I have a database for employee. These are the following tables involved: User - contains email, password, companyId Profile - ...
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62 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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1answer
342 views

Attempting to identify transitive dependency

Hello I am attempting to identify a transitive dependency in the following diagram. I think that possibly the determinate of "Subtotal" is "Quantity" and "Price Charged" but I'm not sure if "subtotal" ...
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1answer
57 views

Design for hierarchical embedded database

The goal is to construct a hierarchical database of Objects having the following format: TypeA -> ObjectA [values, contains ObjectB*, ObjectC*, etc.] TypeB -> ObjectB [values, contains ...
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1answer
63 views

Need some recommendations on organizing data

I'm new here. This question, to my mind, is allowed by the rules I saw in the "2 minute tour". If I got it wrong, no need for nasty grams. I'll delete if enough people say so. But anyway, I have a ...
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1answer
58 views

Maximum normalization

I have been studying the normal forms rules to guide me with database design and data storage, the problem I am having is that once I optimize for the first normal form (1NF), I figured I may well ...
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2answers
396 views

To normalize or not to normalize for few distinct values

Assuming in a Postgres database, you have a table called party, which can have less than 5 well-defined party_types such as 'Person' or 'Organization'. Would you store the party_type in the party ...
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315 views

Lossy Decomposition meaning

Suppose I have a relation R=(A,B,C,D) and I decompose it into: R1=(A,B,C) R2=(A,D) then if it is said that the decomposition is lossy,then what is the meaning of that statement?I have an ...
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1answer
287 views

Normalisation of practise database [closed]

I am a newbie to database design, and I'm a bit confused about how to create a database with minimum redundancy. Suppose I have a table abc with repetition of data in it and no two rows are same. Now ...
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129 views

Can somebody check this normalisation workings i think i am missing a step or a dependency somewhere

given these two tables: and: I need to first list them as an un-normalised structure(s) then i need to identify the functional dependencies/primary keys. Once i have done this i must represent ...
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2answers
235 views

Can somebody help me normalise this database/check my workings

I am new to database design/normalisation and functional dependencies. I have started a new database class in school this week and we have been given a worksheet that requires the following: This is ...
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108 views

Normalise the database, struggling to understand how i can normalise this

Cross post warning: I recently found dba.stack exchange so i thought it would be better to post there: ...
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1answer
509 views

Functional dependencies and candidate key example [closed]

Hi there I'm still learning for my examination and I got this exercise: A table is given: F-Name, F-Nation, Team-Name, Team-Nation ...
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4answers
2k views

How to handle table design with variable columns

I have a table design scenario and as a non-DBA type, would like opinions on which is more scaleable. Say you are asked to record information on houses for a metro area, starting with a small ...
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248 views

Normalizing data to 3NF

I need some help with normalization. Here is the data in 0NF : **HOSPITAL SERVICES (date_hospitalization , id_patient , id_doctor , name , surname , PIN, duration_of_hospitalization , ...
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307 views

Can Anyone please review my database after I did the Normalization ?.Any suggestion is appreciated

User: User_ID,user_name,E-mail Staff: User_ID,Fname,Lname,DOB Student: User_ID fname Lname DOB Lecture: User_ID Admin: User_ID Position ID : P_ID,ROLE_NAME, Staff_position ...
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1answer
160 views

Scheme review/Normalization level/query optimization

So I have a relatively complex database I'm designing - basically full in-house accounting setup. In one section I have some concern that I'm over-normalizing; the 'directory' - I'll example the ...
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2answers
58 views

Best design for a many:many relationship issue

We have three types of entity, each with their own table: table:A(a_id), table:B(b_id), table:C(c_id) Each of these entities can have any number of email addresses and linked Twitter accounts. ...
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1answer
49 views

How to relate 2 tables to a third when the first 2 tables have a relationship?

For once, I find myself at an utter loss in terms of coming up with a good question title. Consider the three following tables. Each has additional columns, but only the columns relevant to the ...
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1answer
29 views

Normal form for a relation where the number of tuples having the same value in a column is the same for all the possible values in that column

Is there a normal form for a relation that would permit the following table : id | alpha ---------- 1 | a 1 | b 1 | c 2 | g 2 | u 2 | k . . . n | x n | y n | z But not this table : id | ...
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2answers
628 views

Decomposition of a relation to 2NF and 3NF

I am trying to solve this example, but for now I can't. Can somebody show me, step by step how to decompose this to 2NF and then to 3NF? R = {ABCDEF, ABC -> EF, B -> E, E -> D} key of this ...
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1answer
119 views

How can I normalize this database?

I've got legacy ecommerce database, which is awfully designed and I need to move all products from it to new solution. But I stuck with how product properties stored. So it basically has tens of ...
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1answer
30 views

Effectively modelling extended classes

I have 3 different types of content for a website, 'Article', 'Video', 'Review'. Each of those three types of content contain common fields and type specific fields. For this, I have created the ...
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1answer
125 views

Normalise an expenditure table in a budget database [closed]

We have a budget database that stores expenditure items per budget. There are over 100 expenditure items each having common attributes: Amount, Frequency, Comment. The table will have over 300 ...
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3answers
536 views

Database design for bookmark system

I am creating a bookmark system where people can save their bookmarks. Each user has its own personal page with bookmarks. A bookmark should have atleast one tag and max five. Each user can create ...
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1answer
2k views

Two-column foreign key constraint only when third column is NOT NULL

Given the following tables: CREATE TABLE verified_name ( id SERIAL PRIMARY KEY, name TEXT NOT NULL, email TEXT NOT NULL, UNIQUE (name, email) ); CREATE ...
2
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1answer
125 views

To normalize or not to normalizde? (10 fields)

I'm helping someone to design a database and for a specific case I'm not sure. I have 10 fields - this will never change - that will always be filled and used in every query that could be coming up. ...
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3answers
751 views

Normalization: 'zip code' as a primary key

I've seen frequently that you should not have all address fields (zip, street, city, state, country, etc) in the same table as your user info table (pk_id, name, email... ). This would be in ...
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56 views

Is this table designed properly

I am trying to model the process of where one co-worker enters a statement of their proposed work procedure and another co-worker commenting and approving the statement. Currently I have one table as ...
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1answer
155 views

If all variables are a subset of the candidate key, is the database design 5NF?

I have a table called LogMessages, which has the following columns: Level A numeric value which represents Trace, Debug, Info, Warning, Error or Fatal Time A UTC time Message Foreign key to a ...