In a column of type formula, the DATE_ADD() function displays a date which is the addition of a date from a column of type date and a number X of days.
The first parameter is the exact name of a date column.
The second parameter is an integer number which corresponds to the number of days I want to add. This number can be positive or negative.
DATE_ADD(Send estimate, 3)
I have added 3 days to my Send Quote date.
DATE_ADD(Customer delivery, -4)
I have subtracted 4 days from my Customer Delivery date.