I have oracle sqlplus/Discoverer/Forms in my laptop. But, earlier i was connected to my company's network, so I had database connection. Now, how can I use these softwares, as I do not have any database name.
Is there a way to create a database without altering or disturbing these softwares. If there is a way, could anyone of you guide me in doing so.
In order to save you some time and avoid a headache, consider installing Oracle database into different home (directory) than you used for tools you already have.
Also, don't panic if you won't be able to connect to a newly created database using an old SQL*Plus - it just won't find the path to it - you'll have to adjust TNSNAMES.ORA (and, probably, SQLNET.ORA) (both can be found in \network\admin directories). In order NOT to lose aliases to the company database, append newly created database into an existing TNSNAMES.ORA.
However, as it becomes complicated to mantain both (or even multiple .ORA files - which could happen if you decide to install another Oracle products), you could consider creating an operating system environment variable called TNS_ADMIN and point it to a single .ORA file(s), kept in desired directory (not necessarily one of the \network\admin ones).
By installing Oracle Database Express Edition, will I be able to use the existing softwares-Discoverer/Forms, which are already present in my system. And, what about the existing SQL PLUS if I install Oracle Database Express Edition.