连接PL/SQL Develper时出现如题所示的错误，提供一种可能的解决办法如下：

打下E:\oracle\product\10.1.0\Db_1\NETWORK\ADMIN（如果目录不一样就搜索文件名）下的tnsnames.ora文件，将以下的HOST = hkx改为HOST = localhost：

ORCL =

  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = hkx)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )

改为：

ORCL =

  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )