I use 8 columns in mine
It isn't as complicated as it sounds though
The columns are:
Day
Date
Number of days since start
Units
Craving
Bottle Start
Bottle End
Drinks outside home
The columns in green above are the main ones obviously
The first three make it easy to sort or plot trends - e.g. are there patterns (that I don't already know

), or to plot nice graphs
The two columns in red, I just put a 1 if I start/finish a bottle on that day - that way, since I know how many units are in a bottle, I can double check my consumption - which can be easily understimated if you have a 'heavy hand' when pouring drinks
The final column in orange, I use to track the number of units I drink when I go out - which are normally easier to track than those I drink at home (and it makes it easier to track how many I drink at home by seeing how long each bottle lasts)