code: @Override
    public DDF sql2ddf(String command, Schema schema, DataSourceDescriptor dataSource, DataFormat dataFormat) throws DDFException {
      //    TableRDD tableRdd = null;
      //    RDD<Row> rddRow = null;
  
      DataFrame rdd = this.getHiveContext().sql(command);
      if (schema == null) schema = SchemaHandler.getSchemaFromDataFrame(rdd);
      DDF ddf = this.getManager().newDDF(this.getManager(), rdd, new Class<?>[]
                      {DataFrame.class}, null, schema);
      ddf.getRepresentationHandler().cache(false);
      ddf.getRepresentationHandler().get(new Class<?>[]{RDD.class, Row.class});
      return ddf;
    }
docs: TODO: SparkSql