The meta-interpretation will not say anything more than "this query may modify facts' database". Anything above that requires actual interpretation with rollbac

The meta-interpretation will not say anything more than "this query may modify facts' database". Anything above that requires actual interpretation with rollback of changes. Because, you know, of halting theorem. Last time I checked, rollback of changes made into facts database was not even a notion in Prolog language. There was no notion of transaction in Prolog. "meta-interpretation" of SQL statement amounts to looking at the statement type, whether it is an INSERT/DELETE/UPDATE or just a SELECT query. There is no much complexity in the SQL syntax. My first experience writing more or less non-toy parser was to parse SQL schema, it was 20 years ago. SQL is not harder than VHDL with its context-sensitive lexing phase, where you can't answer is '(' a character literal or is it a part record type value construction. Maybe, DELIMITER can bite you, but, again, it is not hard to parse with parsing combinators.