１.配置内容：

1).listener.ora

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = D:/oracle/product/10.1.0/Db_1)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (SID_NAME = orcl)
      (ORACLE_HOME = D:/oracle/product/10.1.0/Db_1)
      (global_dbname = orcl)
    )
    (SID_DESC =
      (SID_NAME = PRACTICE)
      (ORACLE_HOME = D:/oracle/product/10.1.0/Db_1)
      (global_dbname = PRACTICE)
    )
    (SID_DESC =
      (SID_NAME = RCAT)
      (ORACLE_HOME = D:/oracle/product/10.1.0/Db_1)
      (global_dbname = RCAT)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = doone.pan)(PORT = 1521))
      )
    )
  )

2).tnsnames.ora

orcl =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = doone)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )
rcat =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = doone)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = rcat)
    )
  )
PRACTICE =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = doone)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = PRACTICE)
    )
  )
EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

２.说明

1).连接时可以用conn user/pwd@orcl,conn user/pwd@ract,conn user/pwd@practice

2).多库时，不配置上面两文件，可能出现的问题.

a.conn user/pwd 如果直接用这样连接，默认连到最后建的那库上

b.ORA-01041: internal error. hostdef extension doesn't exist.

  出现这原因，一般是tns没配置对应库说明.　导致库关闭后，重启出现问题

c.ORA-12170: TNS:Connect timeout occurred

  出现这错误，一般是listener.ora没配置对应库说明

d.ORA-12514: TNS:listener does not currently know of service requested in connect
descriptor　

出现这错误，一般是listener.ora没配置对应库说明