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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questions
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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 ...
4
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2answers
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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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1answer
34 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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1answer
114 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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1answer
74 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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1answer
32 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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1answer
25 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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1answer
30 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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0answers
52 views
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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2answers
69 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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votes
3answers
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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
73 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 ...
0
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1answer
31 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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3answers
391 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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1answer
178 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
63 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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2answers
48 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 ...
2
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0answers
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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
897 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
33 views
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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2answers
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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 ...
2
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1answer
49 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 ...
2
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1answer
180 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 ...
3
votes
1answer
190 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 ...
2
votes
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 ...
2
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1answer
141 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
228 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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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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1answer
57 views
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
116 views
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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1answer
87 views
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
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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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0answers
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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
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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
38 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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vote
1answer
34 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. ...
2
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0answers
56 views
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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0answers
168 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 ...
1
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1answer
174 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
491 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
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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 ...
2
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1answer
163 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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2answers
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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 ...
2
votes
1answer
66 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 ...
