Rails: select unique values from a column

Question

I already have a working solution, but I would really like to know why this doesn\'t work:

ratings = Model.select(:rating).uniq
ratings.each { |r| puts r.rat         


        

Answer 1

If you're going to use Model.select, then you might as well just use DISTINCT, as it will return only the unique values. This is better because it means it returns less rows and should be slightly faster than returning a number of rows and then telling Rails to pick the unique values.

Model.select('DISTINCT rating')

Of course, this is provided your database understands the DISTINCT keyword, and most should.