small query compiler progress

src/sql/query_intermediates.cpp

@@ -23,6 +23,12 @@ record query_select_finish::fetch_one()
   return *connection_.fetch(compiler.compile(&data_)).begin().get();
 }
 
+std::string query_select_finish::str() const
+{
+  query_compiler compiler(connection_.dialect());
+  return compiler.compile(&data_).sql;
+}
+
 std::unique_ptr<query_result_impl> query_select_finish::fetch()
 {
   query_compiler compiler(connection_.dialect());