After using Import Table data to import data from an Excel sheet, the casing for the entries "TRUE" or "FALSE" are changed to mixed/init caps. This is only an issue with the terms true and false.
Excel file written to and saved with data like:
Data in database after import through Toad's Import Table Data:
Add an apostrophe before the terms 'true' or 'false', i.e. 'TRUE and 'FALSE.
Save the Excel file as a csv file and then import it, using Toad's import table data.