updating a record with select

Hello,

I have displayed a list of people and now i want to assign them a
relation for example .... friend, brother,stranger,etc. the list of
relations is stored with me.
How can I use the select option(probably have to use onchange) so that
the moment i select the relation the record of the person is updated.
The name of the table from where i have to pick the relations is
"relations"

Person model
belongs_to :person

relation model
has_many :people

show.rhtml in view
<%@people.each do |person|%>
<tr>
<td><%=$i%></td>
<td><%= link_to (image_tag(person.public_filename(:thumb)),
person.public_filename) rescue nil%></td>
<td><%=link_to
person.title,:controller=>"person",:action=>"edit",:id=>person.id%></td>
<td><%=link_to
person.first_name,:controller=>"person",:action=>"edit",:id=>person.id%>
<td><%=link_to
person.last_name,:controller=>"person",:action=>"edit",:id=>person.id%></td>
<td><%=link_to
person.email1,:controller=>"person",:action=>"edit",:id=>person.id%></td>
<td> select statement goes here.......what should be written here</td>
<%$i = $i+1%>
</tr>

Thank you.