`mix ecto.create`抛出奇怪的localhost：5432连接错误

Question

这是我第一次使用Elixir + Phoenix。我只是尝试运行mix ecto.create，但出现以下错误：

    19:08:28.529 [error] GenServer #PID<0.295.0> terminating
** (DBConnection.ConnectionError) tcp connect (localhost:5432): connection refused - :econnrefused
    (db_connection) lib/db_connection/connection.ex:84: DBConnection.Connection.connect/2
    (connection) lib/connection.ex:622: Connection.enter_connect/5
    (stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3
Last message: nil
State: Postgrex.Protocol
** (Mix) The database for DwayneFM.Repo couldn't be created: killed

任何想法可能是什么原因造成的？ 提前致谢。