From: Brian Candler <b.candler@...>
Date: 2008-12-30T05:45:59+09:00
Subject: Re: Creating a class for returing DB results

You're close. Wrap the actual code which does the action in another 
instance method, such as 'process_rows'. Then to 'return' multiple 
values, the Ruby way is to yield them to a block which the caller 
passes.

> Class Countdb
>    attr_accessor :mydb, :dbuser, :dbpw, :table, :mycode
> 
> require 'DBI'
> 
>  def initialize(mydb, dbuser, dbpw, table, mycode)
>    @mydb = mydb
>    @dbuser = dbuser
>    @dbpw = dbpw
>    @table = table
>    @mycode = mycode
>  end

  def process_rows
> 
>  dbh= DBI.connect(mydb,dbuser,dbpw)

change these to @mydb, @dbuser, @dbpw (ditto table to @table and mycode 
to @mycode below)

>     sth = dbh.execute("SELECT count(*) FROM #{table} where code =
> #{mycode}")
>        while row = sth.fetch do
>          finalcount=row[0]      #How do I return this value?

   yield row[0]

>          end
>        sth.finish
>     # disconnect from server
>     dbh.disconnect if dbh

  end
> end

> I think we can then instantiate this object via:
> mydbcount = Countdb.new(val1, val2, val3, val4, val5)

That creates an instance of the object and sets the instance variables 
such as @mydb etc.

After this the caller would then do something like this:

mydbcount.process_rows { |data| p data }
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