How can I count the number of records that have a unique value in a particular field in ROR?

Question

I have a record set that includes a date field, and want to determine how many unique dates are represented in the record set.

Something like:

Record         


        

Answer 1

the latest #count on rails source code only accept 1 parameter. see: http://api.rubyonrails.org/classes/ActiveRecord/Calculations.html#method-i-count

so I achieved the requirement by

Record.count('DISTINCT date')