Sorry for the very late reply. I've attached the samples to the original post. Here's the situation:
I have huge files from different sources with common key fields (Client number and product number).
In one file, I have the date of subscription (dates of order placement), in the other file, date of response (delivery date).
The file containing date of response is corrupted with different types of data (other than dates). Also, for some entries, the date of response is older the date of subscription. Several entries have the same date of subscription and of response but are for different clients and one client can have different types of products.
I have to calculate the difference between the two dates but also do a moving average for say every 3 days and display the results in a chart. (However, the number of entries, having similar dates but concerning different clients, is quite random from one month to another)
Thank you so much for your help,