The Ultimate Cheat Sheet on Normalization 1NF 2NF 3NF for Database Students
What is Normalization and Why is it Important?
Normalization is a formal process of decomposing relations with anomalies to produce smaller, well-structured and stable relations. It is primarily a tool to validate and improve a logical design so that it satisfies certain constraints that avoid unnecessary duplication of data. Normalization is important because it helps to achieve the following goals: - Reduce data redundancy and inconsistency by eliminating duplicated data in different relations. - Ensure data integrity and avoid update anomalies by enforcing referential integrity constraints and functional dependencies. - Enhance query performance by reducing the size of relations and indexes, and simplifying join operations. - Facilitate data security and privacy by allowing different levels of access to different relations based on user roles and privileges. The Concept of Functional Dependencies
Before we can understand the normal forms, we need to introduce the concept of functional dependencies. A functional dependency is a constraint between two sets of attributes in a relation. It states that the value of one attribute (the determinant) determines the value of another attribute. For example, in a relation Employee(EmpID, Name, DeptID, Salary), we can say that EmpID -> Name, which means that the employee ID determines the employee name. This implies that if two rows have the same value of EmpID, they must have the same value of Name. Functional dependencies are determined by the meaning and semantics of the data, not by the actual values in the relation. Therefore, we cannot infer functional dependencies just by looking at the data, but we can verify them by checking for violations. Functional dependencies are important because they help us to identify the key attributes of a relation, and to ensure that the relation is well-structured and free of anomalies. The Normal Forms: 1NF, 2NF, 3NF and BCNF
The normal forms are a series of tests on a relation to determine whether it satisfies or violates the requirements of a certain level of normalization. The higher the normal form, the more normalized the relation is. The most common normal forms are: First Normal Form (1NF)
A relation is in first normal form if it has only atomic attributes (simple, single-valued) and a primary key has been identified. Every relation is in 1NF by definition. For example, the following relation Student(StudentID, Name, CourseID, CourseName, Grade) is in 1NF because it has only atomic attributes and StudentID is the primary key. Second Normal Form (2NF)
A relation is in second normal form if it is in 1NF and every non-key attribute is fully functionally dependent on the primary key. This means that there are no partial dependencies, where a non-key attribute depends on only part of a composite primary key. For example, the following relation Employee(EmpID, DeptID, Name, Salary) is not in 2NF because Name and Salary depend only on EmpID, which is part of the composite primary key (EmpID, DeptID). To bring this relation to 2NF, we need to split it into two relations: Employee(EmpID, Name, Salary) and Department(DeptID, EmpID). Third Normal Form (3NF)
A relation is in third normal form if it is in 2NF and every non-key attribute is non-transitively dependent on the primary key. This means that there are no transitive dependencies, where a non-key attribute depends on another non-key attribute that depends on the primary key. For example, the following relation Student(StudentID, Name, Address, SubjectID, Subject) is not in 3NF because Subject depends on SubjectID, which depends on StudentID. To bring this relation to 3NF, we need to split it into two relations: Student(StudentID, Name, Address, SubjectID) and Subject(SubjectID, Subject). Boyce-Codd Normal Form (BCNF)
A relation is in Boyce-Codd normal form if it is in 3NF and every determinant is a candidate key. This means that there are no functional dependencies where a non-key attribute determines a key attribute. For example, the following relation Course(CourseID, Professor, Subject) is not in BCNF because Professor -> Subject, and Professor is not a candidate key. To bring this relation to BCNF, we need to split it into two relations: Course(CourseID, Professor) and Subject(Professor, Subject). How to Normalize a Database
The Process of Normalization
The process of normalization involves the following steps: - Identify all the candidate keys of the relation. - Identify all the functional dependencies of the relation. - Examine the functional dependencies and determine the highest normal form that the relation satisfies. - If the relation is not in the desired normal form, decompose it into smaller relations that satisfy the higher normal form. - Repeat the process for each of the smaller relations until all of them are in the desired normal form. The Benefits of Normalization
Normalization has many benefits for database design and management, such as: - It reduces data redundancy and inconsistency by eliminating duplicated data in different relations. - It ensures data integrity and avoids update anomalies by enforcing referential integrity constraints and functional dependencies. - It enhances query performance by reducing the size of relations and indexes, and simplifying join operations. - It facilitates data security and privacy by allowing different levels of access to different relations based on user roles and privileges. - It improves data quality and accuracy by making it easier to validate and maintain data. The Drawbacks of Normalization
Normalization also has some drawbacks that need to be considered, such as: - It may increase the complexity of the database schema by creating more relations and foreign keys. - It may require more join operations to retrieve data from multiple relations, which may affect query performance and efficiency. - It may not reflect the natural structure and semantics of the data as perceived by the users or applications. - It may not meet some specific requirements or constraints that are not captured by the normal forms. Therefore, normalization should be balanced with other factors such as user needs, application requirements, performance issues, and data analysis. How to Download a PDF on Normalization 1NF 2NF 3NF
Sources of PDFs on Normalization 1NF 2NF 3NF
There are many sources of PDFs on normalization 1NF 2NF 3NF that you can find online. Some of them are: ResearchGate
ResearchGate is a social network for researchers and academics. You can find many PDFs on normalization 1NF 2NF 3NF from various publications and authors. For example, you can download a PDF titled "NORMALIZATION IN DBMS (NORMAL FORMS)" by Nilu Singh from K L University. Villanova University
Villanova University is a private Catholic university in Pennsylvania. You can find many PDFs on normalization 1NF 2NF 3NF from its computer science department. For example, you can download a PDF titled "Chapter 4 Normalization" by Mirela Damian. University of Pannonia
University of Pannonia is a public university in Hungary. You can find many PDFs on normalization 1NF 2NF 3NF from its information technology department. For example, you can download a PDF titled "DATABASE NORMALIZATION" by Zoltán Kovács. Steps to Download a PDF on Normalization 1NF 2NF 3NF
To download a PDF on normalization 1NF 2NF 3NF from any of these sources, you can follow these steps: - Go to the website of the source that you want to download from. - Search for the topic or the title of the PDF that you want to download, such as "normalization 1nf 2nf 3nf pdf download". - Browse through the search results and find the PDF that matches your criteria and interest. - Click on the link or the button that allows you to download or view the PDF. You may need to sign up or log in to access some PDFs. - Save the PDF to your device or open it in your browser or PDF reader. Conclusion
Normalization is a formal process of decomposing relations with anomalies to produce smaller, well-structured and stable relations. It is based on the concept of functional dependencies and the normal forms: 1NF, 2NF, 3NF and BCNF. Normalization has many benefits for database design and management, but it also has some drawbacks that need to be balanced with other factors. You can download a PDF on normalization 1NF 2NF 3NF from various sources online by following some simple steps. FAQs
Q: What is the difference between 3NF and BCNF? A: The difference between 3NF and BCNF is that 3NF allows functional dependencies where a non-key attribute determines a key attribute, while BCNF does not. For example, in a relation Student(StudentID, Name, Advisor), Advisor -> StudentID is a functional dependency that violates BCNF but not 3NF. Q: What are some examples of update anomalies? A: Some examples of update anomalies are: - Insertion anomaly: adding a new row forces the user to create duplicate data. For example, in a relation Employee(EmpID, DeptID, Name, Salary), adding a new employee who has not taken any class requires the user to enter a null value or a dummy value for DeptID. - Deletion anomaly: deleting a row may cause loss of other data representing completely different facts. For example, in a relation Employee(EmpID, DeptID, Name, Salary), deleting an employee who is the only one in a department may cause loss of information about that department. - Modification anomaly: changing data in a row forces changes to other rows because of duplication. For example, in a relation Employee(EmpID, DeptID, Name, Salary), giving a salary increase to an employee who has taken multiple classes forces the user to update multiple records with the same value. Q: What are some examples of transitive dependencies? A: Some examples of transitive dependencies are: - In a relation Student(StudentID, Name, Address, SubjectID, Subject), Subject depends on SubjectID, which depends on StudentID. - In a relation Book(BookID, Title, AuthorID, AuthorName), AuthorName depends on AuthorID, which depends on BookID. - In a relation Order(OrderID, CustomerID, CustomerName, ProductID, ProductName), CustomerName depends on CustomerID, which depends on OrderID. Q: What are some sources of PDFs on normalization 1NF 2NF 3NF? A: Some sources of PDFs on normalization 1NF 2NF 3NF are: - ResearchGate: a social network for researchers and academics. You can find many PDFs on normalization 1NF 2NF 3NF from various publications and authors. - Villanova University: a private Catholic university in Pennsylvania. You can find many PDFs on normalization 1NF 2NF 3NF from its computer science department. - University of Pannonia: a public university in Hungary. You can find many PDFs on normalization 1NF 2NF 3NF from its information technology department. Q: How can I download a PDF on normalization 1NF 2NF 3NF? A: To download a PDF on normalization 1NF 2NF 3NF from any of these sources, you can follow these steps: - Go to the website of the source that you want to download from. - Search for the topic or the title of the PDF that you want to download, such as "normalization 1nf 2nf 3nf pdf download". - Browse through the search results and find the PDF that matches your criteria and interest. - Click on the link or the button that allows you to download or view the PDF. You may need to sign up or log in to access some PDFs. - Save the PDF to your device or open it in your browser or PDF reader.
Normalization 1nf 2nf 3nf Pdf Download
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