登录PLSQL Developer时有一个”Database“选项，这是能过tnsnames.ora文件中进行配置的。文件地址在$ORACLE_HOME\NETWORK\ADMIN\文件夹中；

我的是：D:\app\Administrator\product\11.2.0\dbhome_1\NETWORK\ADMIN\tnsnames.ora。

而在登录PLSQL Developer时，是根据在”环境变量“中变量名为 "TNS_ADMIN" 中得到变量值为“D:\app\Administrator\product\11.2.0\dbhome_1\NETWORK\ADMIN”这个地址的。

 

tnsnames.ora中的内容为（本人的）：

# tnsnames.ora Network Configuration File: D:\app\Administrator\product\11.2.0\dbhome_1\network\admin\tnsnames.ora

# Generated by Oracle configuration tools.

LISTENER_ORCL =

  (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))

 

ORACLR_CONNECTION_DATA =

  (DESCRIPTION =

    (ADDRESS_LIST =

      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))

    )

    (CONNECT_DATA =

      (SID = CLRExtProc)

      (PRESENTATION = RO)

    )

  )

 

#以下是你的实例,如：

ORCL =  

(DESCRIPTION =

    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))

    (CONNECT_DATA =

      (SERVER = DEDICATED)

      (SERVICE_NAME = orcl)

    )

 )