How you want to create daywise qvds? Are you going to create from Database table or you already have a big QVD and you want to generate daywise qvds from this big QVD?
There are few steps you need to perform.
1) First time, you need to create day wise qvds for each date using for loop.
2) For Next time onward, Consider that we have stored QVDs as Data_20161231 (i.e. Data_YYYYMMDD).. we need to find out which one is the last date of QVD stored. This can be done using For Each file loop.
3) Find out new data which are > max date and create QVD for it.
So better to provide us right information to help you further.