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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How to normalize a lookup table containing NULL? - or should I bother?

I have a table fee listing different fee descriptions and another table fee_amount holding the amount of the fee. The fee amount is different for each year, whether it's a joint fee or not and what ...
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Should I create a table replicating a CDN (ex. S3 storage bucket)? [closed]

This question can pertain to any CDN, but I am specifically using AWS' S3 and MySQL. Currently I have about 50 different tables that have columns referencing media stored in a single S3 bucket. For ...
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29 views

BCNF decomposition step without functional dependencies

I am performing the BCNF decomposition for the relation R = (A, B, C, D, E), that has the set of functional dependencies AB -> C, CD -> A, C -> E, and C -> B. After checking that the ...
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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 ...
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How to normalize a database which uses tables as references to other tables?

I'm trying to create the database for my application, but I cannot manage to normalize my data on a MySQL database. I have a Types of map entity The Types must have one or more Models associated to ...
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33 views

Database design - logging of same value when recorded in multiple tables

I need to record changes to a particular value, which is read as part of multiple events that are all separately tracked, and be able to view a log of all of the values later. I think an example will ...
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28 views

Schema design for an entity with 'heterogeneous' status types

Consider a notification system which gets some event data and list of business email addresses as input (the list is basically computed by looking at which users/addresses are subscribed to which type ...
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4answers
85 views

Trouble deciding what/how many tables to use; normalisation suggests one

More of a conceptual question for the community, as I am not "thinking with databases" as much as I would like to just yet. I am using Oracle Database 18c Express Edition with SQL Developer. I have ...
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41 views

Store timeseries data in normal SQL database

I have got historic data of around 20 machine sensors with a time resolution of one second stored in csv-files which need to be imported to a SQL database prior to further data handling and analysis. ...
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11 views

What normal form is table with two self-determining attributes?

I have table with these attributes: employee_id (PK) [...other non-important attributes...] user_account_id There are 2 functional dependecies: employee_id -> user_account_id user_account_id -&...
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Structure to represent matches between teams or individuals

Say there's a sport that can either be contested between two individuals, or two teams comprised of several individuals. So obviously we need the standard players, teams and teams_players tables. But ...
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Normalization of a Database - Is primary key = candidate key?

I'm given a database called Projects where I know that id, pid, sid is the primary key. My goal is to decompose this database such that each sub-relation is in BCNF or 3NF. P(id,pid,sid,sn,pn,mid,mn) ...
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47 views

how to professionally normalize my database - screenshots included

Hello database administrators. I got some excel spreadsheet with data of "my customers" and I'd like to create professionally designed database out of it. Can anyone tell me how this data should be ...
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One to many relationship for constant data

I am saving a book inside a database, so that it can be properly queried. The book I'm working with has constant data. Not a character of it will be changed in the future in any way, once the book has ...
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44 views

Removing duplicates (deduplifying) from an existing, huge, table

I have a huge table. Each row has an ID, some columns which relate to that ID specifically, a short (DNA) Sequence, and some columns which relate to that sequence particularly. If these have not yet ...
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272 views

Why is it considered that a set unnormalizes a database absolutely?

In order for a relationship to be on 1NF it needs to have all values as atomic, if there's a set it's not even in that first normal form: But intuitively I think that a table with that set would be ...
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I need to put the data from the diagram in 3NF [closed]

This is a simple list table of a company trying to keep track of employee assignment to company projects (in other words, not a database but a flat one table file). You will design a database for ...
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Are these tables in 3NF? [closed]

Update: I updated the question to be more specific and also updated the diagram. I am currently in my last semester, I did use SQL before then I left for MongoDB but the practice project requires to ...
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SQLServer: Storing File Extension and normalization?

After much research, I've decided to store pdf/img/txt/doc/etc files on a web server instead of a database. However, the reference to that file will be stored in SQL Server. So far I have... | ...
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32 views

3NF for table layout [closed]

Assuming a table with the following columns UserID, UserName, Console, GameID, GameTitle, GameVendor, VendorCountry, Game Genre, NumberOfPlayers Is this the correct 3NF? Users(UserID,UserName, ...
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31 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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109 views

Normalization of the this relation just want to know what are the functional dependencies

Consider the Customer account database of the ABC big bank, which keeps data for customers and their orders. A database of only one relation is designed, as shown below: ABC( customerNo, ...
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62 views

Why is this relation not in Boyce-Codd Normal Form (BCNF)?

I have the relation (A,B,C,D,E). The relevant functional dependencies are: { E,B,C } → { D } { A,B } → { C } { E,B,D } → { C } { E,A,B } → { D } The candidate key is (E,A,B). I do not understand ...
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66 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 ...
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Does an excessive table violate normalization rules?

Here is an example of some tables that exist in a database where I work. The data isn't actually around schools, but the structure is identical. There are four tables: ** School ** School Id, School ...
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35 views

How do I bring a relation/table to first normal form (1NF) when one of the attributes/columns can hold any number of values?

For example, MOVIES (movieid, movietitle) where movietitle can be any number of words, so I believe it's not atomic. How do you bring something like that to 1NF?
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Is this table really in first normal form (1NF)?

Does this table comply with 1NF, even if CourseNo and StudentNo? Student(StudentNo, StudentName, Major, CourseNo, CourseName, InstructorNo, InstructorName, InstructorLocation, Grade)
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Attempting to identify minimal functional dependencies in a Compact Disc details scenario

I believe this relation/table is in first normal form (1NF): Collection (cd_id, title, label, artist, type, country, song_id, song_title, length) Note: Bold means keys. What I have managed to ...
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61 views

Attempt to decompose up to second normal form (2NF) in a scenario about students and courses

1NF: (student_id, name, start, program, course_code, course_name, faculty, credits, time, grade) Minimal functional dependencies (identified): {student_id} → { name, start, program } {course_code}...
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35 views

How can I normalize this schema about students and courses further?

1NF: I am working on 2NF: student (student_id, name, start, program) course (coure_code, course_name, faculty, credits, time) student_course(student_id, course_code, grade) I am trying to achieve ...
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1answer
66 views

Normalization with two potential primary keys

I have the following STUDENT relation in first normal form, where id has been identified as the primary key (email here is also unique for all tuples): STUDENT(id, email, first_name, last_name) I ...
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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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Does a computed column break 3NF (third normal form)?

From my understanding of 3NF, there should not be any transitive dependency. However, this is what I found from the AdventureWorks2012 database Production.WorkOrder table. Since StockedQty is ...
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38 views

Determining minimal cover of a relation

I am having trouble understanding why a certain set of functional dependencies is not minimal. We have a relation R(A,B,C,D,E,F,G) with the following dependencies F: 1. A->CDE 2. B->FG 3. AB-&...
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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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356 views

Does using composite keys violate 2NF?

From all of the database related reference books that I have come across, there is a universal rule that state a database table should be at least 3NF. From what I understand, a table is considered ...
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77 views

Is there a database table design to avoid storing table names in a table?

So my scenario demands to store details of businesses which offer varied services. One business can offer n different services. Since each service is different, details pertaining to a service are in ...
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51 views

Third Normal Form. Multiple attributes determine another?

Concerning 3NF. If you have a composite non-key determinant to a single non-key dependent, does this violate 3NF? Everything I read on transitive dependencies says one non-key determining another non-...
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31 views

Strategies for Database Schema Redesign on Un-Normalized Group of Order Tables in Inventory System

Being my first database-driven and SQL powered program, I'd created this more or less on-the-fly, learning as I go.. trying to be cautious- but more or less created with the intent of simply working.....
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49 views

Decompose a relation to 2NF and preserve all the functional dependencies

For example, consider the following relation: R(A, B, C, D, E) With the functional dependencies (FDs) shown below: {A→B, BC→E, D→C} Here candidate key is {AD} and the relation is not in second ...
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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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139 views

Deduplication/normalization of string column on insert

I have a database of text tuples. Imagine e.g. full file paths + standard comments. Then you dump large file tree and generate comments for files. A file can have lots of comments, but their text ...
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223 views

Proper normalization for an Orders table--whether to split or no

Each order has a unique SalesOrderNumber. An order is made up of various PartID numbers, each with an associated OrderQuantity number. I have the following table currently in my model: I'm ...
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147 views

Are there relations that cannot be normalized to second normal form (2NF)?

I came across this example that I can't normalize to 2NF, so I was wondering if relations that could not be normalized existed. Here is the example relation: R(A, B, C, D, E) with the functional ...
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33 views

When normalising, if you have entities with the same primary key, does it mean it should be the same entity?

Crrently I have this check in data where each check in has check-in details, activities and total extra items charge(extra items are required for some activities). In UNF, I separated them into 3 ...
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789 views

Database Design for Cars

I'm designing a database to capture car data. Here's a simplified design for capturing year, make, model, and trim: This should handle data like this: 2017 Ford Mustang GT However, it turns out ...
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301 views

How to normalize CSV invoice data?

For flat data which comes in with fields like: name address status class version user mode CSV files are regularly received, with the above as typical columns. ...
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81 views

Normalization: Should I do this in 2NF or 3NF?

Consider a database storing the data of invoices, and each invoice takes the following form: Invoice_Num: 1480 Handled By: John Keaton Staff Num: 263 Staff Position: Trainee Item_Num Item_Desc ...
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126 views

Way around Composite Primary Key requiring Composite Foreign Key

Here is a table called Make (where name is the PK) name|other columns ---------------------- A | ... B | ... C | ... And a table called Type (where make, name together is the PK and make ...
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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 ...