Query to add an integer (day) to a date

This would be far easier to do just by writing an expression using Query Entity to fetch the date from the row in question and then add the number of days to it.  In general I strongly recommend against using the Query DB nodes like this unless there's absolutely no other option.

You can fetch the date and the no of days to be  added from the database to expression rule using the query entity and follow the below code for the desired Output. If you want to add multiple data you can use forEach().

a!localVariables(
/* Fetch the date and no of days to be added using query entity*/
  local!date:today(),
  local!noOfDays:2,
  local!result:local!date+local!noOfDays,
  local!result
)