我先装了oracle10g，然后再安装了8i。用10g的sqlplus，连接8i创建的数据库，提示无法解析的用户名，应该是tnsnames.ora没用设置好。后来用10g连接8i的数据库提示：ora-03134：Connections to this server version are no longer supported.
原因貌似是oracle8.17跟10.1.0.2不兼容，好像升级10g的应用程序就可以，不知oracle搞什么鬼。
在8i的sqlplus直接用（/as sysdba）登录就可以连上数据库但是指定数据库名（ as sysdba）就会提示：无法处理用户名的问题,解决办法：
原来tnsnames.ora文件内容为：
# TNSNAMES.ORA Network Configuration File: D:\oracle\product\8.1.7\Db_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.
EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1522))
)
(CONNECT_DATA =
(SERVICE_NAME= orcl8i)
)
)
修改后的tnsnames.ora内容：
# TNSNAMES.ORA Network Configuration File: D:\oracle\product\8.1.7\Db_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.
EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1522))
)
(CONNECT_DATA =
(SERVICE_NAME= orcl8i)
)
)
ORCL8I =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1522))
)
(CONNECT_DATA =
(SERVICE_NAME = orcl8i)
(INSTANCE_NAME = orcl8i)
)
)
之前一直以为有(SERVICE_NAME = orcl8i)就可以了，原来前缀ORCL8I=(DE*****)也是需要的。
刚好解决这个问题，贴出来仅供参考。