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14 Terms
Normalization
it is a design technique that is widely used as a guide in designing relational databases. Its theory is based on the concepts of normal forms.
Normal forms
are sets of rules describing what we should do or not do in our table.
relational table
is said to be a particular normal form if it satisfied a certain set of constraints.
Normalization Process
It consists of breaking tables into smaller tables that forms a better design. In addition, it is the process of decomposing relations with anomalies to produce smaller, well-structured relations.
Well-Structured Relations
It is a relation that contains minimal data redundancy and allows users to insert, delete, and update rows without causing data inconsistencies.
Mutual independence
means that no non-key column is dependent upon any combination of the other columns. The first two normal forms are intermediate steps to achieve the goal of having all tables in 3NF.
Functional Dependency
It is a set of constraints between two attributes in a relation. Functional dependency says that if two tuples have same values for attributes A1, A2,..., An, then those two tuples must have to have same values for attributes B1, B2, ..., Bn.
Insertion anomalies
This means that that some data cannot be inserted in the database. Likewise, adding new rows forces user to create duplicate data.
Update/Modification anomalies
If data items are scattered and are not linked to each other properly, then it could lead to strange situations. For example, when we try to update one data item having its copies scattered over several places, a few instances get updated properly while a few others are left with old values. Such instances leave the database in an inconsistent state.
Deletion anomalies
We tried to delete a record, but parts of it was left undeleted because of unawareness, the data is also saved somewhere else. In addition, deleting some data cause other information to be lost. Likewise, deleting rows may cause a loss of data that would be needed for other future rows.