The variable I select contains special character '&' - I even tried to change the character into "AND" then save the updated table on my user schema and try to read and select it again. I am getting the same error. any Idea how I can resolve this issue?
The error message is from Oracle, not SQL Server, so presuming you are using Toad for Oracle....
Can you please re-post to the Toad for Oracle Forum, and give readers much more details about your use case, especially the steps that lead to the error message...
e.g. are you trying to update a table? define a datatype in your table? etc.
Screen shots are always helpful.