Solve bugs from v1

[ngrislain]

• Probably not worth solving (SQL v1) but if I use twice the same colulmn that gets aliased, the aliased one does not get any value (to be checked if v2 does it properly, but Nicolas seems to be confident)
  

• Probably not worth solving because v1 but if I do the same count twice with aliases this time, I get the exact same results (I was expecting two separate evaluation, though it is debatable)
  

• Worth solving (in SQL v2), making sure that COUNT(column_name) only counts non null values (today it's equivalent to count(*)
  

• worth checking in SQL v2, sum (case when else if end) not working
  

• not sure what's happening here (it works with target_epsilon=0)