Hi, i have a group of sales data with multiple transaction,i am trying to use the sales data to find out the timeframe of different campaign of promotion. Within the transaction data, each item have multiple transaction and different discount. i will sort the data by the amount of discount first in order to get the date of different promotion. but now i wanted to abstract of first and last date of each campaign to determine the start date and the end date of the promotion. (this is a school project, that is why we are given limited data). Thank you