SJSU CMPE 226 - Normalization (11 pages)

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Normalization



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Normalization

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Pages:
11
School:
San Jose State University
Course:
Cmpe 226 - Database Systems
Database Systems Documents

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Overview of Normalization By R E Wyllys University of Texas Austin Introduction One of the more complicated topics in the area of database management is the process of normalizing the tables in a relational database These notes are intended to provide you with an overview of this topic which I hope will be helpful to you after you have gained some familiarity with the ideas of and techniques used in normalization The underlying ideas in normalization are simple enough Through normalization we want to design for our relational database a set of files that 1 contain all the data necessary for the purposes that the database is to serve 2 have as little redundancy as possible 3 accommodate multiple values for types of data that require them 4 permit efficient updates of the data in the database and 5 avoid the danger of losing data unknowingly The primary reason for normalizing databases to at least the level of the 3rd Normal Form the levels are explained below is that normalization is a potent weapon against the possible corruption of databases stemming from what are called insertion anomalies deletion anomalies and update anomalies These types of error can creep into databases that are insufficiently normalized An insertion anomaly is a failure to place information about a new database entry into all the places in the database where information about that new entry needs to be stored In a properly normalized database information about a new entry needs to be inserted into only one place in the database in an inadequately normalized database information about a new entry may need to be inserted into more than one place and human fallibility being what it is some of the needed additional insertions may be missed A deletion anomaly is a failure to remove information about an existing database entry when it is time to remove that entry In a properly normalized database information about an old to be gotten rid of entry needs to be deleted from only one place in the



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