change_column_null

# File activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb, line 473
      def change_column_null(table_name, column_name, null, default = nil)
        unless null || default.nil?
          exec_query("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
        end
        alter_table(table_name) do |definition|
          definition[column_name].null = null
        end
      end