When I import data from an Excel spreadsheet, I lose any leading zeros that are in my data.
1) Open the Excel spreadsheet and save it as a tab delimited file or csv file, which ever fits your scenario better.
2) When doing the import, select to import from a Text file.
3) When selecting a file, choose the newly created delimited file.
4) Continue with the import as normal.
Note: Leading zeros will only be saved if the datatype of the column you are importing to is Varchar2.
