If you have ecc system installed in top of HANA DB you can use : WORKDAYS_BETWEEN
example:
- create a Scripted Calculation view
WORKDAYS_BETWEEN(#Calender ID#, #Date 1#, #Date 2#), #Schema# ( As a Default : 'SAPNHP' ) ) AS"DIFF_DAYS"
Documentation:
WORKDAYS_BETWEEN - SAP HANA SQL and System Views Reference - SAP Library