Need SQL Script/Logic to size an identified subset of a table
I am attempting to do some forecasting related to an archiving project, however, I don't know how to size a subset of the table.
For example, Table A has a 15 month online policy. Therefore, on a monthly basis, we will archive one month worth of data. By doing a simple count(*) function, I can get a row count but I want to know how many bytes/GB's I will be removing from the table on a monthly basis.
Please provide a SQL script/logic that will assist me in this query.