Question

Imagine the scenario,

I have a table Day_fee(date(Date),fee(Integer))

I want to have a list with only the months of the table, for example:

Day_fee
date(Date)  fee(Int)
----------|---------
2012/03/27   1
2012/03/26   2
2012/03/25   2
2012/05/01   3
2012/05/02   3
2012/07/01   2
2013/04/01   2
2013/05/01   1

The result => a list with 03, 05 and 07 , without repeat the months.

And the other big question:

I would want a hash o list with month and year, for example {“03″=>”2012″,”04″=>”2013″,”05″=>”2013”, “05”=>”2012″, “07”=>”2012″} , without repeat the months, maybe the table can have more years with the same month

Beacuse, after that, i want to show a html table with the months and paginate that.

Thoughts?

Thanks for your help.

Answer 1

Try this:

If you are using Postgres DB

# Postgres
DayFee.sum(:fee, :group => "EXTRACT(MONTH FROM date)")

=> #<OrderedHash {"3" => 5, "5"=> 6, "7"=> 2}

If you are using MySQL

DayFee.sum(:fee, :group => "MONTH(date)")

Edit

Based on your comment, it looks like you want a different data:

Postgres

DayFee.count(:fee, :group => "date_trunc('month', date)").
  map{|d, k| Date.parse(d)}.
  inject({}){|h, d| h[d.month]=d.year;h}

MySQL

DayFee.count(:fee, :group => "DATE_FORMAT(date, '%Y-%m')").
  map{|d, k| Date.parse(d+"-00 00:00")}.
  inject({}){|h, d| h[d.month]=d.year;h}

To get a 2D array

DayFee.count(:fee, :group => "date_trunc('month', date)", 
    :order => "date_trunc('month', date) ASC").
  map{|d, k| Date.parse(d)}.
  map{|h, d| [d.month, d.year]}

# [["03", "2012"], ["03", "2013"], ["03", "2014"]]

To get hash with collection of years

DayFee.count(:fee, :group => "date_trunc('month', date)").
  map{|d, k| Date.parse(d)}.
  inject({}){|h, d| (h[d.month]||=[]) << d.year;h}

# {"03" => ["2012", "2013", "2014"]}