OQL Module
==========

Currently, this API provides a technique for recording information about a
query (the class to be operated on, type of operation, query restrictions)
and can generate SQL to implement this operation, for either the MySQL or
PostgreSQL database systems.

a set of functions exist which place the data into a structure, and then the
oql_query_as_sql() takes this data and a database type as arguments, and
creates the appropriate query. (note: currently the SQL is created once, and
then cached. The query structure can not be reused either for another
database or with additional restructions. There is no option to remove
restrictions from a query.

Ideally, only the objectstore module will call this function, as that should
be the only module that requires the SQL, or knows what particular database
is in use.

The database type identifier does not have to match the database in use.
While currently, MySQL and PostgreSQL are both different database types, and
different identifiers recognised by the OQL module, an 'SQL92' identifier
will be useful for many databases that have a sufficient degree of
compatability.


