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Keep in mind that the query engines for SQL Server and VFP are not identical. For more detailed/complicated queries (subqueries, embedded CASE statements vs IIF, etc.) the query syntax will be different across databases.

Depending on your requirements, it may be difficult for your query engine to produce a SQL SELECT statement that can run against multiple back-ends. (Unless your query 'builder' takes into account the differences, or unless you're writing stored procedures in the database).
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Even in cases where the (simple) queries *can* be identical for all backends, they should be exposed somehow/somewhere so they can be optimized for different environments if at all possible.

Otherwise you're going to be writing queries for the lowest common denominator, in terms both of functionality and speed. In various cases, I've done this myself (ease of maintenance, most generic, up-migration requirements etc), but in the end I've always ended up either moving the logic to build the final query someplace I could examine it and tune it for each back-end... or wishing I could do so.

>L<