Developing Efficient SQL Statements

http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/sql_1016.htm#i30971

The ways you can improve SQL statement efficiency:

·         Verifying Optimizer Statistics

·         Reviewing the Execution Plan

·         Restructuring the SQL Statements

·         Restructuring the Indexes

·         Modifying or Disabling Triggers and Constraints

·         Restructuring the Data

·         Maintaining Execution Plans Over Time

·         Visiting Data as Few Times as Possible