You can also use ADODB to connect to unopened spreadsheets and manipulate them using SQL (As long as they are in database format) This tutorial explains how.
All our tutorial samples are free however if you appreciate our work and would like to make a voluntary donation then please do.
Both the below books by John Walkenbach are fantastic books and he is a brilliant author, I would recommend picking one of these books up even if just for a reference. I have read power programming cover to cover and it is easy to follow and is a must have for any serious VBA programmer.
If you have read any books and feel they are worth recommending then please post about them on our Forum.