oracle的sys与sysdba用户有什么区别？？

sys是用户，sysdba是权限，要说关系只能说sys用户拥有sysdba的权限。

sys　就和linux/unix　里面的root用户　拥有超级权限
sysdba 不是个用户吧　可以是个有特殊权限的连接模式　　至于区别嘛　看下面的例子
[clark@rhel3 bbed]$ sqlplus system/oracle

SQL*Plus: Release 11.2.0.4.0 Production on Fri Nov 28 16:20:01 2014

Copyright (c) 1982, 2013, Oracle. All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> shutdown immediate
ORA-01031: insufficient privileges
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[clark@rhel3 bbed]$ sqlplus system/oracle as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Fri Nov 28 16:20:19 2014

Copyright (c) 1982, 2013, Oracle. All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL>