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2. Database normalization - Wikipedia

   en.wikipedia.org/wiki/Database_normalization

   Database normalization is the process of structuring a relational database in accordance with a series of so-called normal forms in order to reduce data redundancy and improve data integrity. It was first proposed by British computer scientist Edgar F. Codd as part of his relational model .

3. Fifth normal form - Wikipedia

   en.wikipedia.org/wiki/Fifth_normal_form

   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.

4. Third normal form - Wikipedia

   en.wikipedia.org/wiki/Third_normal_form

   The third normal form (3NF) is a normal form used in database normalization. 3NF was originally defined by E. F. Codd in 1971. [2] Codd's definition states that a table is in 3NF if and only if both of the following conditions hold: The relation R (table) is in second normal form (2NF).

5. Domain-key normal form - Wikipedia

   en.wikipedia.org/wiki/Domain-key_normal_form

   Domain-key normal form (DK/NF or DKNF) is a normal form used in database normalization which requires that the database contains no constraints other than domain constraints and key constraints. A domain constraint specifies the permissible values for a given attribute, while a key constraint specifies the attributes that uniquely identify a ...

6. First normal form - Wikipedia

   en.wikipedia.org/wiki/First_normal_form

   Database normalization is the process of representing a database in terms of relations in standard normal forms, where first normal is a minimal requirement. SQL-92 does not support creating or using table-valued columns, which means that using only the "traditional relational database features" (excluding extensions even if they were later ...

7. Fourth normal form - Wikipedia

   en.wikipedia.org/wiki/Fourth_normal_form

   Fourth normal form (4NF) is a normal form used in database normalization. Introduced by Ronald Fagin in 1977, 4NF is the next level of normalization after Boyce–Codd normal form (BCNF). Whereas the second , third , and Boyce–Codd normal forms are concerned with functional dependencies , 4NF is concerned with a more general type of ...

8. Boyce–Codd normal form - Wikipedia

   en.wikipedia.org/wiki/Boyce–Codd_normal_form

   Boyce–Codd normal form (BCNF or 3.5NF) is a normal form used in database normalization. It is a slightly stricter version of the third normal form (3NF). By using BCNF, a database will remove all redundancies based on functional dependencies .

9. Snowflake schema - Wikipedia

   en.wikipedia.org/wiki/Snowflake_schema

   Normalization splits up data to avoid redundancy (duplication) by moving commonly repeating groups of data into new tables. Normalization therefore tends to increase the number of tables that need to be joined in order to perform a given query, but reduces the space required to hold the data and the number of places where it needs to be updated if the data changes.