在ORACLE安装主目录，products》11.20》NETOWRK》ADMIN》listener.ora添加蓝色字体的SID信息。
SID_LIST_LISTENER_DELL =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = /u01/app/oracle/product/10.2.0/db_1)
(PROGRAM = extproc)
)
(SID_DESC =
(GLOBAL_DBNAME = dell)
(ORACLE_HOME = /u01/app/oracle/product/10.2.0/db_1)
(SID_NAME = dell)
)
)
ORA-12505 错误解决
原文：http://my.oschina.net/JiangTun/blog/384970
