When I connect to DB, always connects as tempdb
It seems the DBA who has created your login has set tempdb as your default database. You may request him/her to do the change at login definition level as per this article. By default, if none of them are mentioned, user connects to master database. You may use below command:

sp_modifylogin login_name, defdb, "your_database"


Kindly note that above command needs to be run at Sybase Database level and only a System Administrator or System Security Officer can execute sp_modifylogin.

As already suggested by Markp, you can issue the command use &lt;database_name&gt; for changing your database. Alternatively you may use database name in the connection string itself.

Below is an example of isql for connecting to "your_database"

isql -S"Server_Name" -U"Login" -D"Your_Database" -P"Password"


You may refer below for isql options:

http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.infocenter.dc30191.1570100/doc/html/san1367605044069.html

Hope above helps.