Adobe ColdFusion 8 Web Application Construction Kit, Volume 1: Getting Started

Indexes

Database applications make extensive use of a table’s primary key whenever relationships are used. It’s therefore vital that accessing a specific row by primary key value be fast. When data is added to a table, you have no guarantee that the rows are stored in any specific order. A row with a higher primary key value could be stored before a row with a lower value. Don’t make any assumptions about the actual physical location of any rows within your table.

Now take another look at the relationship between the movie list table and the expenses table. You have the database scan the expenses table to learn which movies have incurred expenses on specific dates; only rows containing that date are selected. This operation, however, returns ...