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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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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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2answers
58 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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Functional dependency from statement [on hold]

relation about a module unique code, adopted books, and lecturers MODULE( CODE, BOOK, LECTURER) Every lecturer adopts the same books for a particular module. Is this relation normalised? Assume 1NF. ...
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Normalisation for a table that contains user information that could be transitively dependant [on hold]

I have a table that holds user information as such: userId | email | username | pass | firstname | lastname -------|----------------------|------------|------------|---------...
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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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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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1answer
66 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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1answer
54 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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38 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 ...
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2answers
716 views

Is a table without a primary key normalized?

In a lecture, my lecturer showed us a table without a primary key. Upon questioning, he said that in 3NF when you remove transitive dependencies it's ok to then have a table without a primary key. ...
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Its my class project about Normalization to 3NF. I need help in this project?

I just want to know the normalization I have done is correct or there any mistake? Please tell me. enter image description here
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1answer
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Different categories of missings

Most database systems can represent missing values, typically as "Null" or something similar. But what if I want to represent different categories of missing data? For categorical data, this is ...
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Is saving disk space still considered an advantage of normalization?

I have read a while back that one of the advantages of normalization is to save disk space (since normalization minimizes redundancy), but is saving disk space still considered an advantage of ...
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2answers
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A table with many null values VS many tables

Basically my level of DB knowledge enables me to create, select, delete and some simple things. When it comes to designing for performance, I have absolutely 0 knowledge. So my question here is let ...
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1answer
45 views

Is a functional dependency on a “child” table allowed in third normal form (3NF)?

Consider two simple tables, OrderHeader and OrderDetail which contain, respectively, the data shown below: OrderHeader | OrderHeaderID | CustomerID | OrderTotal | |---------------|------------|------...
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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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1answer
171 views

BCNF decomposition does not prevent insert anomaly?

I am in the process of designing a schema for a simple polling app and have tried to normalize it with the decomposition algorithm from this lecture. Requirements A poll has a unique id (poll_id), a ...
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1answer
154 views

Normalizing/combing mutliple tables with similar data

I'm working on setting up a database of vehicle records based on data from a third party vendor. There are 3 models: Vehicles, Transmissions, and Adaptors. Both Vehicles and Transmissions are 1:n ...
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1answer
61 views

Primary key: (a) set it on a single column for two distinct data points or (b) set it on a combination of two columns, each for a separate data point?

I am designing a database for an e-commerce company. Each product will be identified by a unique ID (SKU). We want to format the SKU as LLLL000. LLLL is the parent product, for example Iphone X. 000 ...
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1answer
90 views

Can anyone help me understand the following paragraph?

I was reading Database Systems Design, Implementation and Management by Carlos Coronel. In the chapter of Normalization after he explained 3NF, he writes The existence of multiple candidate keys ...
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1answer
185 views

MongoDB aggregation $unwind and 1NF

I have a basic rhetorical/theoretical question for people experienced using both MongoDB and RDBMS. Surprised SO has no Data Munging or Data Engineering forum. In making an aggregation pipeline in ...
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72 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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Problem in testing normal form [closed]

In the question given in the link https://www.hackerrank.com/challenges/database-normalization-6/problem the answer is 2. But I cannot understand why all the relations are not in BCNF (Since for all ...
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1answer
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For BCNF decomposition, is it okay to have a relation with none of the original functional dependencies?

Given the relation R[c, f, g, h, e, j, a, b, d, i] with the below functional dependencies I have come up with the below solution. However, I am unsure about it, considering R8 has none of the listed ...
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Is this a good database design or transition? Normalize to Denormalized for Data Warehousing [closed]

As of now in sql server , we have a data and a series normalized table structure that is connected to a C# web app (Human Resource / Recruiting System) (slightly medium (or small 12,000 rows.) size ...
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1answer
72 views

Using NULL values for foreign key with normalization

I am creating a table as follows: Building (PK: buildingID) Area (PK: areaID, FK: buildingID) Room (PK: roomID, FK: buildingID, FK: areaID) All rooms are in a building. Some rooms can be in an area ...
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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
27 views

Keeping reference in an array format

I have a design with an orders table and products table. Each order can have many products, so 1 order N products. The default design would be to have something like this: orders table order_id, ...
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2answers
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Modeling Sellers and Products

I'm trying to model product and seller information. The seller can be either an individual, or a company, or a company with branches (and the product is being sold by a particular branch). Each ...
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1answer
33 views

Are these relations in BCNF?

I have a homework question that I am trying to understand but having a tough time with this question. Any explanation or even pointers would be very appreciated (no exact answer expected - I am trying ...
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1answer
32 views

How to reconstruct functional dependencies from 3NF decomposition?

I have the following decomposition for the relation R(A,B,C,D): R1 = (A,B), R2 = (B,C), R3 = (A,D). It is given that AD is the only candidate key for the original relation and that R is not in BCNF. ...
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Surrogate foreign keys allow inconsistent data - which normal form does this violate?

We have inherited a system which has surrogate keys on every table (that is, an auto-increment primary key, id). All of the foreign key constraints are on individual surrogate keys, and this seems to ...
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155 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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1answer
149 views

How to solve multiple minimal covers for functional dependencies?

I have the schema: a,b,c,d,e,g and the following functional dependencies: b->c, dg->ce, bc->dg, e->a, g->bd for which I want to find the minimal cover. It seems that more than one ...
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1answer
364 views

How to find minimal cover when attributes have equal chance to be not necessary?

I have the schema which consists of 6 attributes: t,s,r,w,e,g. For the schema I have the following functional dependencies: s,w --> r;t,w,g --> r,e;s,r --> t,g; e -->w; g --> t,s;r,w,...
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2answers
63 views

Normalizing the Test Table

I'm a web developer looking to leverage more of the power of my RDBMS. I'm currently learning about normalization of data and database design. In the book that I am reading, we started off with one ...
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1answer
152 views

Is sql_variant compatible with First Normal Form (1NF)?

1NF rule says that we should not keep data of different types in one single column. Does it mean that sql_variant is not compatible with first normal form hence should not be used?
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Normalizing data past initial db design phase

I wanted to poke at everyones brain to better understand when it makes sense to normalize a table that carries redundant data. I recently worked on a project at my startup and really question myself ...
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1answer
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Designing a join table for max n records

I know that a basic rule for designing a relational dataset is to not do things like this: create table Order ( OrderID int indentity(1, 1) not null, -- PK CustomerID int identity(1, 1) not ...
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1answer
58 views

Questions Concerning the Chase Test

For the question above, my work for each of the questions is below the concerns. Here are my main concerns: Does the order in which you use the relations matter? Can you end up with less tuples with ...
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1answer
37 views

Question concerning minimal/cannonical cover

For the question above, I am confused with how to approach simplifying the left hand side of BDCE->A. Do I get rid of E, as D depends on it, or do I get rid of CD as well, as CD->A? Here's what I ...
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3answers
219 views

What normalization rules does this table break

Our previous DBA got fed up with the development teams frequent requests to change the database schema to add and delete columns. He then advised to the developers that he would create simple tables ...
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38 views

Decomposition to 3NF

I need the help with following question as part of my assignment / homework Provided the following structure CLASS(Reg-NO ,Unit-ID,UnitTitle,Lecturer,Office) The following functional dependencies ...
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1answer
38 views

Name for a “lookup” table with values in separate rows

I am looking to put a name on a particular situation. When you remove a comma-delimited column and split it into separate rows in a new table, what is that type of table called? In the example below,...
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58 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
143 views

Decomposition in 3NF using synthesis

I have an assignment at the university and it is about decomposition. These are the relation and FDs. V={ABCDEF},F={AB→CD,ABDE→F,BC→A,C→DF} We need to find candidate keys, canonical cover(basis) and ...
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1answer
51 views

3NF Normalization Problem Employing an Algorithm

I'm getting stucked in figuring out how to obtain the third normal form (3NF) using an algorithm ( removing attributes and then functional dependencies ). The relation R( A,B,C,D,E,F,G,H,I,J,K ) has ...
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3answers
436 views

How to transfer data from denormalized table to normalized tables in Oracle?

Hi I currently have a database set up with a table like this: Grades: student name|class name|overall|hw|test|quiz|project|val where student name and class name are type varchar2 with the rest being ...
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1answer
80 views

How to prevent null foreign key during database normalization?

I'm rather new to databases and am having a hard time trying to figure out how to structure my database. This database contains students, classes and all their grades both overall and in categories (...