+ (declare (ignore query-expression full-set result-types))
+ (signal-no-database-error database)
+ (values nil nil nil))
+ (:method (query-expression (database database) &key full-set result-types)
+ (declare (ignore query-expression full-set result-types))
+ (warn "database-query-result-set not implemented for database type ~A."
+ (database-type database))
+ (values nil nil nil))