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Summary


To round up, here's what we covered in this chapter.

Concepts

  • Entities are things, and relationships are the links between them.

  • Relations or tables hold a set of data in tabular form.

  • Columns belonging to tables describe the attributes that each data item possesses.

  • Rows in tables hold data items with values for each column in a table.

  • Keys are used to identify a single row.

  • Functional dependencies identify which attributes determine the values of other attributes.

  • Schemas are the blueprints for a database.

Design Principles

  • Minimize redundancy without losing data.

  • Insertion, deletion, and update anomalies are problems that occur when trying to insert, delete, or update data in a table with a flawed structure.

  • Avoid designs that will lead to large quantities of null values.

Normalization

  • Normalization is a formal process for improving database design.

  • First normal form (1NF) means atomic column or attribute values.

  • Second normal form (2NF) means that all attributes outside the key must depend on the whole key.

  • Third normal form (3NF) means no transitive dependencies.

  • Boyce-Codd normal form (BCNF) means that all attributes must be functionally determined by a superkey.





MySQL Tutorial
MySQL Tutorial
ISBN: 0672325845
EAN: 2147483647
Year: 2003
Pages: 261
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