Issue with form_tag in rails

I am using form_tag in my create.html.erb file. Under this form_tag there is a button. Now I wish that after clicking the button the page will be refreshed only ,I dont want to redirect anywhere . So what should I write in my form tag as path?

For session controller my view/sessions/create.html.erb file is:

<h4>Database contents here:</h4>

<table>                         
<tr>  
<th>ID</th>                        
<th>AGE</th>
<th>NAME</th>
</tr>
<% @data.each do |data| %>       
<tr>
<td><%= data.id %></td>  
<td><%= data.age %></td>  
<td><%= data.name %></td> 
</tr>
<% end %>                        
</table> 

<div>

<%= form_tag :method => :get do %>
  <%= button_tag type: 'submit'  do %>
     <%= content_tag :div do%>
        <h4>View Data </h4><h4><%= @num %></h4>
     <% end %>
    <% end %>
<% end %>
</div>

And my contollers/sessions_controller file is:

class SessionsController < ApplicationController
def new
end

def index
end

def create
user = User.authenticate(params[:email], params[:password])
 @data=Information.all
 @num=Information.count()
 @tym=Time.now.getutc
if user
  session[:user_id] = user.id
  #redirect_to root_url, :notice => "Logged in!"

  #this part is for showing the content of the information table


  respond_to do |format|
  format.html
  format.xml { render xml: @data }
  end
else
  flash.now.alert = "Invalid email or password"
  render "new"
end



end

def destroy
 session[:user_id] = nil
 redirect_to root_url, :notice => "Logged out!"
 end
end