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Database Access
Database access requires two kinds of
information:
- Which records are to be selected. This takes the form of a set of
restrictions that selected records must satisfy.
(restrict 'field value)
- What information is to be retrieved from the selected records.
(retrieve 'field)
The task of the NL access program is to translate the user's question
from English into a formal call to an existing database program.
The components of the query are collected as lists in the global
variables restrictions and retrievals.