Need help with a workflow

[abdullah_noor23]

I need to build a workflow where it reads new data from an excel file and populates that data to a database table called SCD. Every time there is a new excel file the workflow compares it with the existing data in SCD table.  The Database Table has 4 extra columns. Effective Start Date, Effective End Date, Date Created, Date Modified. 

I set Date Created and Date Modified  to DateTimeNow().

Note: Effective Start/End dates need to be Datetime values. Round to nearest minute. Multiple updates may occur during the day, all changes should be captured).

• SCD table: update Effective End Date on changed records
• SCD table: append records with changes with Effective Start Date = Effective End Date + 1 minute [Specially need help with this part as both effective start and end date is in DateTime, my sql isn't working in the formula tool.]

Can anyone help with this workflow? I replicated the input data and SCD table as an attachment.