I have an Oracle SQL Developer installed in my machine and able to connect/query Database.
Now, I need to connect database via Load Runner, write SQL query in vugen script, retrieve database column values, store it to parameter, which then I can substitute into my web_custom_requests.
Any help on this is much appreciated.
Read the section in the manual on creation of Oracle virtual users.
Read the section on multiprotocol virtual users.
You are adding load that is not present in production. This is not recommended. Export the data you need and place it in a file or virtual table server.