define rating column in table?
You better use tinyint. It's int from 0 to 255. It's also takes only 1 byte to store value. It's enough for your 5-star rate.
If you need store values like 4.5 stars you may store stars like this:
1 star =10
2.5 stars=25
and so on
And, of course, you need check constraint on this field.

tinyint - using storage 1 byte
numeric(1)/decimal - using storage 5 bytes