APEX

Hello everyone.

I have a minor problem in uploading CSV file to HTMLDB.
I don't know the exact reason, but HTMLDB threw
"ORA-20001: Unable to create collection: ORA-06502: PL/SQL: numeric or value error" whenever I tried to upload my csv file. after a few repetition of deleting potential problem-causing columns and trying again, I found out the following:

when numeric value and character value are stored together in single column, the upload fails. For example, we have a column which stores the employee number. The employee number is just a sequential numeric value, however temporary employees have 'T' in front of their employee number, so it begins something like T0032 and so on.

So, then, I tried to enclose all the employee numbers which start with numeric value with " character, but that would just simply take too long to do it manually, and excel does not seem to support enclosing the values with " when it's saving the spreadsheet with CSV format.

So, I'm kind of stuck right now.
Can anyone give me a good way to deal it?
THANK YOU!