Special Edition Using Access 97, Second Edition

Using Access Indexes

Database managers use indexes to relate the values of key fields to the location of the data entity on the disk. The basic purpose of an index is to speed up access to specific rows or groups of rows within a database table. You also use indexes to enforce the uniqueness of primary keys and establish upper and lower limits for queries. Using an index eliminates the necessity of re-sorting the table each time you need to create a sequenced list based on a foreign key.

Different PC database managers create and use indexes in a variety of ways. Paradox uses a mandatory primary index (.px) to speed up queries and ensure nonduplicate keys. Secondary indexes on nonprimary-key fields are permitted by Paradox (.x## and .y##) and ...