Rails - Sep 2005 - Computing the MAX for a model's column

I am trying to retrieve the MAX of a column in a model''s table.  I
came up with the following solution, but I would appreciate some
feedback as I am sure there must be a more elegant way.

Here is how I am retrieving the MAX position of an Item model:

Item.find_by_sql("SELECT MAX(position) AS max FROM items")[0].max.to_i
rescue 0

I put the rescue in to handle the empty case.

Thanks,
Tom

Hello Tom,

Tom Davies said the following on 2005-09-17 22:45:
> Here is how I am retrieving the MAX position of an Item model:
> 
> Item.find_by_sql("SELECT MAX(position) AS max FROM
items")[0].max.to_i rescue 0
What you want is ActiveRecord::Base.connection.select_one(), which 
returns a single value or nil:

max_value = ActiveRecord::Base.connection.select_one(''SELECT 
MAX(position) AS max FROM items'')
max_value = 0 if max_value.blank?
max_value = max_value.to_i

Enjoy !
François

Thanks Francois.  That is much better :)

On 9/18/05, rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
<rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org>
wrote:
> Hello Tom,
> 
> Tom Davies said the following on 2005-09-17 22:45:
> > Here is how I am retrieving the MAX position of an Item model:
> >
> > Item.find_by_sql("SELECT MAX(position) AS max FROM
items")[0].max.to_i rescue 0
> 
> What you want is ActiveRecord::Base.connection.select_one(), which
> returns a single value or nil:
> 
> max_value = ActiveRecord::Base.connection.select_one(''SELECT
> MAX(position) AS max FROM items'')
> max_value = 0 if max_value.blank?
> max_value = max_value.to_i
> 
> Enjoy !
> François
> 
>

This is the AR way: 

(may need betagems)

Item.find(:first, :select => ''MAX(position) AS
position").position

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