自动生成编号

Date date = new Date();
            SimpleDateFormat dmDate = new SimpleDateFormat("yyyymMdd"); // 获取当前时间
            String dateran = dmDate.format(datE);
            String sql = " SELEct case when main_number is null then '0001' else substr(max(substr(main_number,7))+1,7) end main_number " +
                         "  from aviation_info where DATE_FORMAT(create_date,'%Y%m%d') = DATE_FORMAT(now(),'%Y%m%d')  ";
            String maxnum = jdbcTemplate.queryForObject(sql,String.class);
            String mainnumber = "HKZD"+dateran+@H_703_6@maxnum;
            aviationInfo.setMainnumber(mainnumber);
            aviationInfoservice.save(aviationInfo);