i want to pick out the old customers in 2011 from 2012
I want to put part of the data from 2011 worksheet into 2012 worksheet, but also want to pick out the old customers of 2011 from 2012 sheet, and join their consumption details in one sheet. So i can know the old customers consumption trends in the last two years. There are columns like Customer ID (unique number for every customer), Date, Products, Costs.
So can you help me?