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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Relation is in 2NF or not?

Suppose a relation(A,B,C,D,E) has 2 candidate keys- ABC ABD And a FD is given as, CD -> E Then is the relation in 2NF? C and D are subsets of 2 different candidate keys and they together are ...
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Relation in BCNF or not

Consider the relation R[A,B,C,D,E] with: the keys {A,E}, {A,B,C} and {A,B,D} the functional dependency {A,C} -> {D} no repeating attributes What is the normal form of R? My answer: It is in 1NF ...
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Multiple choice questions about normal forms [closed]

Can somebody help me with the next multiple choice questions? For 1, I think it's b) because C->D is a transitive dependency. For 2, I think it's a), and for 3, I don't know what to chose.
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Proper relational form for a CRM

I'm designing a multi-tenant CRM. At the moment, my tables look like this: // one "list" per tenant. lists are collections of contacts. lists list_id list_name // a contact usually maps ...
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Normalization using DENSE_RANK and LAST_INSERT_ID

db-fiddle I have created a table called orders (orderId, customersId) and a table called orderDetails (orderId, productId). My goal is to denormalize a table called temp which is like scanId, ...
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42 views

How do I prove this relation is in the `3FN`?

Consider the relation R(A,B,C,D,E) and the set of functional dependencies F={A->D,D->C,BC->AE} I need to prove this relation is in the 3FN, however I don't think it is; in fact, I don't even ...
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MySQL Insert Values Into Normalized Relational Database (multiple tables) at the same time

I have normalised my database to 4NF. How do I now insert values at the same time when records have been split into multiple tables? most of the child tables reference their parent table CUSTOMER ...
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If `AB->C` and `A->B` , `A->C`?

I'm new to databases, is this true? if so, how can we deduce that? I don't know how to use the properties to get an answer, could you help>
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How can I design Person table in MySQL?

I have two person type: Users and Clients. Users can login the panel but clients can't login the panel. My current database: (but this design not good for me. I need to connect these tables to the ...
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Is this the proper way to integrate normalization? [closed]

I'm trying to wrap my head around normalization. Is this the proper way to create a database with this data? How much more effective is it to use a foreign key instead of just repeating AAPL for ...
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How can I design address table?

Hello I need designing addresses table. I designed it but I didn't like it very much. My needs: I have customers and users (admins). I have addresses for customers and users. We need design in ...
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How can I design Address table with different types?

I have a Address table and different address types like Personal and Corporate. I design a table but I think is breaking normalization rules. How can I improve this design? My design:
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What should be the schema of the database if the parent table is being referenced in more than one child table?

I have three entities in my database: Category, SubCategory, and Product. Now the thing is SubCategory is dependent on Category, whereas Product can be dependent on SubCategory or directly either on ...
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BCNF decomposition which generates redundant relations (as for 3NF)

Sometimes the 3NF synthesis decomposition algorithm (such as the one described here p.4) generates redundant relations, where all attributes of some R_i already appear in another R_j. The algorithm is ...
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Database scheme design for complex movie system

I'm creating a complex app for cinemas including frontend and reservation system. I struggle with a DB scheme and this is a worst part for me, I was never good in designing DB's. Easily said it's a ...
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Database normalization for sensor data

I'm working on the backend of a quality evaluation tool. And I hit a the limit of too many columns. SQLSTATE[HY000]: General error: 1005 Can't create table xxx.xxx (errno: 185 "Too many columns&...
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How do I ensure I have split my tables without loss of data?

This is w.r.t Database Normalisation, when I have a redundant table that causes anomalies, I would want to consider splitting it in smaller tables as per the NF rules. BUT Say I split a big table into ...
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Meaning of “Dependency” in Relation to Elementary DB Normalization

In trying to figure out why the following table definitions from a textbook exercise about nurses in hospital wards is not in 2NF: Ward (WName, Location, WType) Ward-Nurse (WName(fk), NurseID, ...
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58 views

JSON vs Record/Struct type in a DB

It seems like some databases have implement a Record/Struct type and others have implemented a Json/Jsonb type to handle nested data structures. A few examples being: BigQuery Struct CockroachDB ...
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database design - table with multiple nullable foreign keys

Context: I have 3 unrelated entities (tables) Entity1, Entity2 and Entity3 I have a table called Operation, which can have multiple targets. A target for an operation can be Entity1, Entity2 or ...
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How can a 'Request' store a 'Result' code and its associated 'Error' code and still enforce the relationship between Result and Error?

I'm an application developer creating the database structure to represent a flat file message format. I'd like to ask the collective knowledge the best/correct way to represent the following scenario:...
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54 views

Postgres normalize human name string

Is there some function to normalize name string: select normalize('R.C. Bray') 'R. C. Bray' Or the opposite direction? The simple replace('. ', '.') or replace('.', '. ') is wrong and may be ...
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More tables or More records performance wise

i am into a scenario that upon looking at the our project database contains Identical tables with the schema described below: id url region_1 region_2 region_3 region_4 date_created My ...
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Is this definition of 5NF right?

From what I've gathered from my textbook, 5NF doesn't allow lossy decomposition, so that when we join tables that are in 5NF, no spurious tuples are generated. The definition in my book states that: &...
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Most efficient table structure for multi-tenant database

I have a conventional relational database (mySQL) with several entities stored in their own table. Three examples are images, events and organisations. We are making a change to the way our site works ...
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Can a table be un-normalizable or am I misunderstanding the theory

I was considering normalizing a flat table (SQLite if its relevant) I'd been working with in a small personal project and it just didn't seem to make sense. Consider an example table like below. Each ...
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Relational-JSON overlapping with association [closed]

I have a composed class called sensor that is linked to a main class Node such that: class node is linked with another node to make a communication that produce an event class sensor can as well ...
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3answers
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Is storing data that can be inferred go against data normalization?

To simplify lets say I have two tables PROJECTS and JOBS. A user creates a project and runs 1 or more jobs using a project. So it would possible look something like this: PROJECTS [PK] project_id ...
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1answer
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How do foreign keys affect partial and transitive dependencies (databases)

I'm struggling to work out how foreign keys can affect partial and transitive dependencies when normalising databases. I have multiple tables, two of which are job offer and accepted job. in job offer,...
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Table normalisation and empty values [duplicate]

Here are two ways I can optimise mapping of a text field with several other attributes to question and answer. First approach is, creating a map table with both question_id and answer_id in which ...
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1answer
32 views

Refactoring out a boolean column [closed]

I have a Pets table (cats, dogs, you name it) with over a million records. For simplicity sake, it looks like the following: Pets Field Type Null Key id int(11) NO ...
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1answer
42 views

Database Normalization Advice [closed]

I have database for multi store application. So, I have 3 type of user thats Admin, Customer, Merchant and I have 3 table for users. User table, Customer table, Merchant table. User Table; id ...
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119 views

Weak Entities + Partial Keys + 2NF [closed]

I'm a bit confused on the concept of weak entities and normalization and couldn't find any answers online. I know that generally weak entities have a partial key to uniquely identify its own records ...
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Celebrities database with multiple parent categories and children categories? [duplicate]

I am creating a React/Laravel web application that will allow the user to search and navigate through celebrities based on their 'categories'. I have set up a Categories table using MySQL like so: *...
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1answer
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Where can I get a proper dataset for performing Normalization techniques? [closed]

I'm new to databases and I just started with learning different techniques of Data Warehousing. I was given an assignment to perform Normalization techniques on a dataset of at least 1000 rows with ...
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Is it correct way having status or Summary columns in parent table or should choose another precedure?

My Parent Table is "Jobs" table, and there is child table that records Job's actions named "JobActions" as below: Jobs (JobId, JobType, CurrentStage, AssignedTo) JobActions (JobActionId, JobId, ...
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168 views

Need Help With BCNF Decomposition Problem

I'll try and keep it as quick and concise as I can: I'm currently a novice developer who's super eager to learn Database Normalization and Optimization so I can up my skill in Full-Stack development, ...
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2answers
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Relationship normalization in SQL Server

I want to know should I remove PersonTypeId from Persons table or is it a good idea to have it in there?
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Alternatives to storing a record with exactly n multiple foreign keys from the same foreign table, where the relationships can't be repeated

Say there are entities called singulars, and entities called relationships. It takes exactly two singulars to make up a relationships entity. That pair of singulars can't be repeated elsewhere in ...
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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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Does one of the normal forms require separation of repeating clusters of values into another table?

Should the repeating values in the "Sales" table below be separated out into a second table as part of the process of database normalization? Note that none of the values are functionally dependent on ...
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Normalization Excercise Clarification

Have a bit of confusion regarding a normalization from 1NF to BCNF. The teacher gave us this excercise to illustrate a normalisation all the way up to BCNF. I think I have found a problem with the ...
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115 views

Database Design: Normalization and NULL values

I have normalized my table from 0NF to 2NF (hopefully correct). How do I now go from 2NF to 3NF? Also, ResponseToTransactionId is a recursive foreign key that will contain NULL values a lot of the ...
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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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63 views

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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1answer
246 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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1answer
48 views

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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42 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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4answers
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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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