102 | Chapter 4: Oracle Data Structures
With the Enterprise Edition of Oracle, youcan add an index to an expression, which
can provide the same performance benefits of an index to the qualities defined as an
expression.
Data Design
Tables and columns present a logical view of the data in a relational database. The
flexibility of a relational database gives youmany options for grouping the individual
pieces of data, represented by the columns, into a set of tables. To use Oracle
most effectively, you should understand and follow some firmly established principles
of database design.
The topic of database design is vast and deep: we won??™t even pretend to offer more
than a cursory overview. For more information, we recommend the book Oracle
Design by Dave Ensor and Ian Stevenson (O??™Reilly; see Appendix B for details).
When E. F. Codd created the concept of a relational database in the 1960s, he also
began work on the concept of normalized data design. The theory behind normalized
data design is pretty straightforward: a table should contain only the information
that is directly related to the key value of the table.
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