Database Normalization.pptx
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The document discusses different levels of database normalization including first normal form (1NF), second normal form (2NF), third normal form (3NF), Boyce-Codd normal form (BCNF), fourth normal form (4NF), and fifth normal form (5NF). Normalization is a technique to reduce data redundancy and eliminate anomalies by organizing attributes and relations. The document provides definitions and requirements for each normalization form with the goal of most databases being at least 3NF or BCNF.
Database Normalization.pptx
- 2. Presented By Md Nazmul Hoque Shourob ID: 201002305
- 3. Content Introduction Levels of Normalization First Normal Form (1NF) Second Normal Form (2NF) Third Normal Form (3NF) Fourth Normal Form (4NF) Fifth Normal Form (5NF) Domain Key Normal Form (DKNF)
- 4. Introduction What is Normalization? Normalization is a database design technique that reduces data redundancy and eliminates undesirable characteristics like Insertion, Update and Deletion Anomalies. This is the process which allows you to winnow out redundant data within your database. A properly normalized database should have the following characteristics Scalar values in each fields --Absence of redundancy. --Minimal use of null values. --Minimal loss of information.
- 5. LevelsofNormalization The database normalization process is further categorized into the following types: First Normal Form (1NF) Second Normal Form (2NF) Third Normal Form (3NF) Boyce-Codd Normal Form (BCNF) Fourth Normal Form (4NF) Fifth Normal Form (5NF) Domain Key Normal Form (DKNF) Most databases should be 3NF or BCNF in order to avoid the database anomalies.
- 6. FirstNormalForm (1NF) A table is considered to be in 1NF if all the fields contain only scalar values (as opposed to list of values). Example (Not 1NF) 0-321-32132-1 Balloon Sleepy, Snoopy, Grumpy 321-321-1111, 232-234-1234, 665-235-6532 Small House 714-000-0000 $34.00 0-55-123456-9 Main Street Jones, Smith 123-333-3333, 654-223-3455 Small House 714-000-0000 $22.95 0-123-45678-0 Ulysses Joyce 666-666-6666 Alpha Press 999-999-9999 $34.00 1-22-233700-0 Visual Basic Roman 444-444-4444 Big House 123-456-7890 $25.00 ISBN Title AuName AuPhone PubName PubPhone Price Author and AuPhone columns are not scalar
- 7. SecondNormalForm (2NF) Second Normal Form (2NF) is based on the concept of full functional dependency. Second Normal Form applies to relations with composite keys, that is, relations with a primary key composed of two or more attributes. A relation with a single-attribute primary key is automatically in at least 2NF. A relation that is not in 2NF may suffer from the update anomalies.
- 8. ThirdNormalForm (3NF) This form dictates that all non-key attributes of a table must be functionally dependent on a candidate key i.e. there can be no interdependencies among non- key attributes. For a table to be in 3NF, there are two requirements : --The table should be second normal form --No attribute is transitively dependent on the primary key
- 9. FourthNormalForm (4NF) A relation will be in 4NF if it is in Boyce Codd normal form and has no multi- valued dependency. For a dependency A → B, if for a single value of A, multiple values of B exists, then the relation will be a multi-valued dependency. Rules for 4th Normal Form : For a table to satisfy the Fourth Normal Form, it should satisfy the following two conditions: It should be in the Boyce-Codd Normal Form. And, the table should not have any Multi-valued Dependency.
- 10. FifthNormalForm (5NF) Fifth normal form (5NF), also known as projection–join normal form (PJ/NF), is a level of database normalization designed to remove redundancy in relational databases recording multi- valued facts by isolating semantically related multiple relationships.