How to use has_many in rails view

Here is the index_controller

  def index
    @categories = Category.all
  end

Here is the two models

1. Category model

has_many :sub_categories

2. sub_category model

belongs_to :category

And your view should contain

<% @categories.each do |category| %>
    <h1><%= category.title %></h1>
    <% category.sub_categories.each do |sub_category| %>
        <%= sub_category.descriptino %>
    <% end %>
<% end %>

phpPgAdmin Configuration for rails

1. cd /etc/postgresql/9.1/main

2. sudo nano pg_hba.conf

3. Change the line from

    local        all        postgres               peer

to

    local        all        postgres               md5

4.  save and exit
5. Then open sudo nano postgresql.conf

6. Change the listen address as listen_address = '*'

7. Now try localhost/phppgadmin 

Get current week of the month and year

Get current week of the current year

select extract(week from date_trunc('month', current_date))

Get current week of the current month

select extract(week from current_date) - extract(week from date_trunc('month',current_date))+1

get last month last and first date

To get last month's last and first date

SELECT (date_trunc('month', now()-interval '6 month')::date - 1) as last_month_date

SELECT (date_trunc('month', now()-interval '6 month')::date ) as first_month_date 

The above query can be used to get last month's last date from current month