# File lib/active_record/connection_adapters/mysql_adapter.rb, line 210
      def change_column(table_name, column_name, type, options = {})
        options[:default] ||= select_one("SHOW COLUMNS FROM #{table_name} LIKE '#{column_name}'")["Default"]
        
        change_column_sql = "ALTER TABLE #{table_name} CHANGE #{column_name} #{column_name} #{type_to_sql(type, options[:limit])}"
        add_column_options!(change_column_sql, options)
        execute(change_column_sql)
      end