abstract class QueriableConnection {
 /**
  * Executes the [sql] query, returning a [Future]<[Results]> that completes 
  * when the results start to become available.
  */
 Future<Results> query(String sql);

 /**
  * Prepares a query with the given [sql]. Returns a [Future<Query>] that
  * completes when the query has been prepared.
  */
 Future<Query> prepare(String sql);

 /**
  * Prepares and executes the [sql] with the given list of [parameters].
  * Returns a [Future]<[Results]> that completes when the query has been
  * executed.
  */
 Future<Results> prepareExecute(String sql, List<dynamic> parameters);
}