sqlplus / as sysdba 与 sqlplus "/ as sysdba" ，10可以省略引号,9里不可以省,但单、双都可以登录

$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.2.0 - Production on Mon Nov 6 18:05:28 2006

Copyright (c) 1982, 2005, Oracle.  All Rights Reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options

SQL>


$ sqlplus '/ as sysdba'

SQL*Plus: Release 9.2.0.5.0 - Production on Mon Nov 6 18:02:53 2006

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.


Connected to:
Oracle9i Enterprise Edition Release 9.2.0.5.0 - 64bit Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.5.0 - Production

SQL> exit
Disconnected from Oracle9i Enterprise Edition Release 9.2.0.5.0 - 64bit Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.5.0 - Production
$ sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.5.0 - Production on Mon Nov 6 18:03:00 2006

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.


Connected to:
Oracle9i Enterprise Edition Release 9.2.0.5.0 - 64bit Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.5.0 - Production