# File lib/better_nested_set.rb, line 301
301:         def before_destroy
302:           return if self[acts_as_nested_set_options[:right_column]].nil? || self[acts_as_nested_set_options[:left_column]].nil?
303:           dif = self[acts_as_nested_set_options[:right_column]] - self[acts_as_nested_set_options[:left_column]] + 1
304: 
305:           self.class.transaction {
306:             self.class.delete_all( "#{acts_as_nested_set_options[:scope]} AND #{acts_as_nested_set_options[:left_column]} > #{self[acts_as_nested_set_options[:left_column]]} and #{acts_as_nested_set_options[:right_column]} < #{self[acts_as_nested_set_options[:right_column]]}" )
307:             self.class.update_all( "#{acts_as_nested_set_options[:left_column]} = (#{acts_as_nested_set_options[:left_column]} - #{dif})",  "#{acts_as_nested_set_options[:scope]} AND #{acts_as_nested_set_options[:left_column]} >= #{self[acts_as_nested_set_options[:right_column]]}" )
308:             self.class.update_all( "#{acts_as_nested_set_options[:right_column]} = (#{acts_as_nested_set_options[:right_column]} - #{dif} )",  "#{acts_as_nested_set_options[:scope]} AND #{acts_as_nested_set_options[:right_column]} >= #{self[acts_as_nested_set_options[:right_column]]}" )
309:           }
310:         end