Join Datatables activity by 3 filters

Hi All!!

I have to join two datatables ( extracted with read range activity from two different excel worbooks) with some conditions by comparing by 3 columns:

columns: Doc , COM and ST

All the columns are in string format and i cant modify the excel due entreprise policy.

Doc column must be match in both
COM column must be match in both
ST column is a date ( in string format dd/MM/yyyy ) must be less or equal

The problem comes in ST column because filter of ST doesnt work properly (join datatable as string are empty) and i don’t know how i have to do it to set a date and use in the filter.

Please could you guide me?

Thanks in advance!!!