File and database normalization

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File and database normalization

• Rationale and procedure outline.

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Normalization of data

• First normal form
• No repeating data sets in records allowed
• Second normal form
• First normal form, and,
• Segregate single key and concatenated key
  dependencies
• Third normal form
• Second normal form, and,
• Remove transitory relationships

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Why do we need to be concerned about the
representation of data?

• Data is at the heart of business transactions
• Data and data bases change constantly
• The structure of data bases change
• Business decisions are based on data
• Systems are built around data.
• The need the ability to view and use data in a
  flexible format, i.e. NORMALIZATION.

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Notes on first normal form

• In general convert non-flat records into 2 or
  more flat records
• Concatenated keys are used to accomplish
  splitting into flat records
• This will result in functional dependencies
• See example

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Notes on second normal form

• Each attribute of a record is functionally
  dependent on the whole key of that record
• If not, then it should be split out
• For each record occurrence the key must uniquely
  identify the record
• No data item in the key must be discarded without
  destroying the property of unique data
  identification
• See example

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Notes on third normal form

• Must be in second normal form
• Each attribute is functionally dependent on the
  key and nothing but the key
• See example

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Pros and cons of normalization

• Disadvantages
• more files
• more records
• more work
• Advantages
• less value redundancy in the records
• faster searches
• less update and search problems
• fewer decision errors

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End file and data base normalization
End file and data base normalization