Standards for storing a rating as a range (1-5, 1 is best, etc.)
Rule of thumb:  The higher, the better.

All that said, I'd suggest to use a lookup table to store rating definitions. Maybe for an specific question you want to use a rating of 0 to 5, but may be tomorrow you need a bigger or a lower ratio.

Or simply you want to change the name of each option.


Elated
Happy
Indifferent
Unhappy
Miserable  


Using a lookup table you can choose different options for different purposes. Sometimes you need 5 options, sometimes 10 and sometimes 2. 

Do not restrict yourself with a 5 options. 


  Life has a lot of flavors:
  
  o  True
     o  False
     o  Do not know/ Do not answer