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Third normal form - Wikipedia, the free encyclopedia
The third normal form ( 3NF ) is a normal form used in database normalization. 3NF was originally defined by E.F. Codd in 1971. Codd's definition states that a table is in 3NF if and only if both ...
en.wikipedia.org/wiki/Third_normal_form |
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Database normalization - Wikipedia, the free encyclopedia
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Whether you're new to the whole concept of databases, or a hard-core database geek, you need to have The Manga Guide to Databases. ... There's something unbelieveably head-spinning about Anime characters discussing SQL, third normal form, distributed databases and transaction concurrency (yes, really).
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Third Normal Form (3NF) is a property of database tables. ... A relation is in third normal form if it is in SecondNormalForm and there are no functional (transitive) dependencies between two (or more) non-primary key attributes.
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In Third Normal Form every value is dependent on the key, the whole key and nothing but the key, so help me Codd... ... Design in Third Normal Form...
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In the third normal form non-key attributes are directly dependent on the primary key attribute. Now, consider the 2 layouts used as example in second normal form. A project may consist of several employees and an employee may work in several projects.
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A schema that uses the same kind of normalization as typically found in an OLTP system. Third normal form schemas are sometimes chosen for large data warehouses, especially environments with significant data loading requirements that are used to feed data marts and execute long-running queries.
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