When i tried to connect to database with test user from SQL prompt then i can connect to it.
SQL> conn test/test
But when i tried to connect with toad with test/test it shows me invalid username/password.
Why is it so?
This is strange for me.
It seems to me you may have an old TOAD version. TOAD prior to 9.5 is capitalizing password strings before sending them to the database and therefore is unable to connect to Oracle 11g unless passwords in your database are capitalized as well or Oracle 11g context sensitive password feature is turned off.
Don't type your password in TOAD when you try to connect and let it popup a dialog box for your password. Type the password in there and it will work. Not sure what they've done in TOAD with passwords but that is a workaround. It has to do with case sensitive passwords in 11g. I think if you change the password to all upper case it will work with TOAD.
The parameter for this is SEC_CASE_SENSITIVE_LOGON http://download.oracle.com/docs/cd/B28359_01/server.111/b28320/initparams.htm#insertedID211
The next problem you'll probably have in 11g is accounts expiring, because they've set a default password expiry time of accounts to 180 days:
Thank you, Thank you, Thank you!
I've been wrestling with this bit of rubbish off and on for over a MONTH! I flipped over to SQL Developer when I really needed a GUI into the database, but the experience was, uh, "not the same."