Minggu, 03 Mei 2009

tugas adsi

1NF

A table on the form said to be normal 1 if did not reside in the unnormalized form of a table, where there is a kind of field multiplication and field that allows a null (empty). Relations, there is a condition in First Normal Form (1NF) if and only if all domains are covered only atomic value, for example, there is no recurrence group (domains) in a tuple. Advantage of the 1NF relation compared Unnormalized (UNRs) is a simplification in the form of representation and ease of use in developing a query language. Its Insuffiency is the need to duplicate data. Most of the system relations (not all) require a form of relations in 1NF.

2NF

The form of normal 2NF met in a table if it meets the form of 1NF, and all the attributes than the primary key, have a full Functional Dependency on primary key. A table does not meet 2NF, if there are attributes that depended (Functional Dependency) are only partial (only depending on the part of the primary key). If there are attributes that have no dependence on the primary key, then the attributes must be moved or removed




3NF

3NF the changes only at the Pegawai table, Because there is no relation with the primary key that has a non-key attributes of each table above and all tables are considered normal up to 3NF.