The document discusses database normalization and different normal forms including 1NF, 2NF, 3NF, and BCNF. The key points are:
- Normalization is the process of organizing data to avoid duplication and anomalies when data is inserted, updated, or deleted.
- First normal form (1NF) requires that each attribute contains atomic values and each table has a primary key.
- Second normal form (2NF) removes subsets of data that apply to multiple rows and places them in separate tables linked through foreign keys.
- Third normal form (3NF) requires that all non-key attributes are dependent on the primary key only, not a non-prime attribute.
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An introduction to database architecture, design and development, its relation to Object Oriented Analysis & Design in software, Illustration with examples to database normalization and finally, a basic SQL guide and best practices
An introduction to database architecture, design and development, its relation to Object Oriented Analysis & Design in software, Illustration with examples to database normalization and finally, a basic SQL guide and best practices
Intro databases
Data – a collection of facts made up of text, numbers and dates: Ali 35000 7/18/86
Information - the meaning given to data in the way it is interpreted:
Mr. Ali is a sales person whose annual salary is $35,000 and whose hire date is July 18, 1986.
A structured collection of related data
An filing cabinet, an address book, a telephone directory, a timetable, etc.
Google and your email is a database
School Student Information System
This is a slide presentation on Database Management System.
Note: All this slide are design by me and licensed under the school I'm currently teaching "Good Shepherd Schools"
Intro databases
Data – a collection of facts made up of text, numbers and dates: Ali 35000 7/18/86
Information - the meaning given to data in the way it is interpreted:
Mr. Ali is a sales person whose annual salary is $35,000 and whose hire date is July 18, 1986.
A structured collection of related data
An filing cabinet, an address book, a telephone directory, a timetable, etc.
Google and your email is a database
School Student Information System
This is a slide presentation on Database Management System.
Note: All this slide are design by me and licensed under the school I'm currently teaching "Good Shepherd Schools"
What is Database NormalizationExplain the guidelines for ensuring t.pdfarjunstores123
What is Database Normalization?Explain the guidelines for ensuring that database are
normalized.
Solution
Here is the answer for your respective question on database normalization:
Before going to know about database normalization we should know about database.
So what is a database?
Its like a repository where all the data related to a particular organization are stored inside the
tables in the form of columns and rows
which can be related to the employees working in that organization or about the finacial and
accounts of the company etc.
While storing data into the tables there might be some problems like duplicate entries of the
same record related to a particular person which creates a problem named data redundancy in the
database.
So to avoid this there\'s been introduced a concept named Normalization.
So what is Database Normalization?
Database normalization or simply called normalization, is the process of arranging or organizing
the columns
and tables of a relational database to reduce data redundancy and improve data integrity and
efficiency of data stored.
Normalization arranges attributes in tables based on dependencies between attributes,
ensuring that the dependencies are properly enforced by database integrity constraints.
Normalization can be achieved by applying some formal rules like synthesis or decomposition.
To come to the types of normalizations there are many.Some of them are as follows:
1NF - First Normal Form
2NF - Second Normal Form
3NF - Third Normal Form
BCNF - Boyce–Codd Normal Form
4NF - Fourth Normal Form
Basic guidelines for normalization:
1NF - First Normal Form:
As per First Normal Form, no two Rows of data must contain repeating group of information.
Each table should be organized into rows and each row should have a primary key that
distinguishes it as unique.
Example for 1NF:
Student Age Subject
Andrea 15 Zoology
Andrea 15 Social Studies
Alan 14 Maths
Stuart 17 Maths
But by using the First Normal Form, data redundancy increases,
as there will be many columns with same data in multiple rows but each row as a whole will be
unique.
2NF - Second Normal Form:
There must not be any partial dependency of any column on primary key.
Meaning that for a table that has concatenated primary key, each column in the table
that is not part of the primary key must depend upon the entire concatenated key for its
existence,failing which the table fails Second normal form.
Example:
Student Age
Andrea 15
Alex 14
Stuart 17
Here we should maintain a separate table for the value subject by doing which we can reduce
data redundancy which is lacking in 1NF.
In the above table,candidate key will be Student column, because all other column i.e Age is
dependent on it.
3NF - Third Normal Form:
Third normal form (3NF) is a database principle that allows you to properly
arrange our tables by building upon the database normalization principles provided by 1NF and
2NF.
There are two basic requirements for a database to be in third normal fo.
The normal forms (NF) of relational database theory provide criteria for determining a table’s degree of vulnerability to logical inconsistencies and anomalies.
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Reverse Pharmacology.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
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Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
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2. Combine Schemas?
Suppose we combine instructor and department into inst_dept
(No connection to relationship set inst_dept)
Result is possible repetition of information
3. Normalization
Database Normalisation is a technique of organizing the data in the
database. Normalization is a systematic approach of decomposing
tables to eliminate data redundancy and undesirable characteristics
like Insertion, Update and Deletion Anomalies.
It is a multi-step process that puts data into tabular form by removing
duplicated data from the relation tables.
Normalization is used for mainly two purpose,
Eliminating reduntant(useless) data.
Ensuring data dependencies make sense i.e data is logically
stored.
4. Problem Without Normalization
Without Normalization, it becomes difficult to handle and update the
database, without facing data loss. Insertion, Updation and Deletion
Anomalies are very frequent if database is not Normalized.
To understand these anomalies let us take an example of Student
table.
5. Problem Without Normalization
Updating Anomaly : To update address of a student who occurs
twice or more than twice in a table, we will have to update S_Address
column in all the rows, else data will become inconsistent.
Insertion Anomaly : Suppose for a new admission, we have a
Student id(S_id), name and address of a student but if student has not
opted for any subjects yet then we have to insert NULL there, leading
to Insertion Anamoly.
Deletion Anomaly : If (S_id) 401 has only one subject and
temporarily he drops it, when we delete that row, entire student record
will be deleted along with it.
6. Normalization Techniques
Normalization rule are divided into following normal form.
First Normal Form (1NF)
Second Normal Form (2NF)
Third Normal Form (3NF)
BCNF
Atomic: Domain is atomic if its elements are considered to be indivisible units
Examples of non-atomic domains: Set of names, composite attributes
Identification numbers like CS101 that can be broken up into parts.
Non-atomic values complicate storage and encourage redundant (repeated)
storage of data. Example: Set of accounts stored with each customer, and set of
owners stored with each account
7. First Normal Form (Cont.)
A relational schema R is in first normal form if the domains of all
attributes of R are atomic.
As per First Normal Form, no two Rows of data must contain repeating
group of information i.e each set of column must have a unique value,
such that multiple columns cannot be used to fetch the same row.
Each table should be organized into rows, and each row should have a
primary key that distinguishes it as unique.
The Primary key is usually a single column, but sometimes more than
one column can be combined to create a single primary key.
8. First Normal Form (Cont.)
For example consider a table which is not in First normal form.
In First Normal Form, any row must not have a column in which more
than one value is saved, like separated with commas. Rather than that,
we must separate such data into multiple rows.
9. First Normal Form (Cont.)
Using the First Normal Form, data redundancy increases, as there will
be many columns with same data in multiple rows but each row as a
whole will be unique.
10. Second Normal Form
Remove subsets of data that apply to multiple rows of a table and place
them in separate tables.
Create relationships between these new tables and their predecessors
through the use of foreign keys.
Although there are a few complex cases in which table in Second
Normal Form suffers Update Anomalies, and to handle those scenarios
Third Normal Form is there.
First
Name
Las t
Name
Address City State Zip
Lisa Hestings Bertha
Street
Miami FL 33157
Adam Gabriel Fleming
Street
Miami FL 33157
Lucy Herts Bridge
Road
NY Sea Cliff 11579
11. Second Normal Form
A brief look at this table reveals a small amount of redundant data.
We're storing the Sea Cliff, NY 11579 and Miami, FL 33157
entries twice each.
Additionally, if the ZIP code for FL were to change, we'd need to
make that change in many places throughout the database.
In a 2NF-compliant database structure, this redundant information
is extracted and stored in a separate table. Our new table (let's call
it ZIPs) might have the following columns-
Zip City State
We’ll need to use a foreign key to tie the two tables together.
We'll use the ZIP code (the primary key from the ZIPs table) to
create that relationship. Here's our new Customers table:
First Name Las t
Name
Address Zip
12. Third Normal Form
Third Normal form applies that every non-prime attribute of table must
be dependent on primary key.
The transitive functional dependency should be removed from the table.
The table must be in Second Normal form. For example, consider a
table with following fields.
Order No Customer No Unit
Price
Quantity Total
123J09 NY65031 500 $ 2 1000 $
120J11 ST90452 300 $ 1 300 $
123J09 NY65031 100 $ 4 400 $
Now, are all of the columns fully dependent upon the primary key?
The customer number varies with the order number and it doesn't
appear to depend upon any of the other fields.
It appears sometimes charge the same customer different prices. The
quantity of items also varies from order to order. So, the unit price and
quamtity is fully dependent upon the order number.
13. Third Normal Form
What about the total?
The total can be derived by multiplying the unit price by the quantity,
therefore it's not fully dependent upon the primary key. We must
remove it from the table to comply with the third normal form.
Order No Customer
No
Price
Price Unit Price Quantity Total
14. Boyce-Codd Normal Form
Boyce and Codd Normal Form is a higher version of the
Third Normal form.
This form deals with certain type of anomaly that is not handled
by 3NF.
A 3NF table which does not have multiple overlapping candidate
keys is said to be in BCNF.