code: public @NotNull OptionalDouble findOptionalDouble(@NotNull @SQL String sql, Object... args) {
          return findOptionalDouble(SqlQuery.query(sql, args));
      }
docs: Finds a unique result from database, converting the database row to double using default mechanisms.
  Returns empty if there are no results or if single null result is returned.
  
  @throws NonUniqueResultException if there are multiple result rows