Result struct returned from any successful query. Its fields are:

• command - An atom of the query command, for example: :select or :insert;
• columns - The column names;
• rows - The result set. A list of tuples, each tuple corresponding to a row, each element in the tuple corresponds to a column;
• num_rows - The number of fetched or affected rows;
• connection_id - The OS pid of the Postgres backend that executed the query;