Question

I’m using Rails & MySql, At the moment, my data shows like this in a view:

Customer A, 5
Customer B, 3
Customer C, 2
Customer A, 2
Customer B, 4

I want it to show like this:

Customer A, 7
Customer B, 7
Customer C, 2

Currently my .html.erb view looks like this:

<% @licenses.each do |l| %>
<tr>
    <td><%= l.customer.companyname %></td>
    <td><%= l.customer.licensecontact %></td>
    <td><%= l.amount %></td>
    </td>
</tr>
<% end %>

I’m pretty sure i need to add something after @licenses.each I’m just not sure what?

Answer 1

From a very little information provided by you, i think You have to use Group BY

SELECT customer, SUM(quantity) AS quantity FROM orders GROUP BY customer

Using Rails 3

Order.select("customer, SUM(quantity) AS quantity").group("customer")

Using Rails 2 #This will work in Rails 3 as well

Order.find(:all, :select => "customer, SUM(quantity) AS quantity", :group => "customer")

EDITED

You have to fetcth the record in something like following way

@licenses = License.find_by_sql("SELECT c.companyname, c.licensecontact, SUM(l.amount) 
                                  FROM licenses l 
                                  LEFT JOIN customers c ON c.id=l.customer_id
                                  GROUP BY c.companyname, c.licensecontact")

Change you view to following

<% @licenses.each do |l| %>
<tr>
    <td><%= l.companyname %></td>
    <td><%= l.licensecontact %></td>
    <td><%= l.amount %></td>
    </td>
</tr>
<% end %>