mysql中根据一个字段相同记录写递增序号，如序号结果，如何实现？

mysql中实现方式如下：

select     merchantId,    NameCn,    send_date,    deliver_name,    deliver_address,    contact,    bill_status,    bill_code,    rankfrom    (select         heyf_tmp.merchantId,        heyf_tmp.NameCn,            heyf_tmp.send_date,            heyf_tmp.deliver_name,            heyf_tmp.deliver_address,            heyf_tmp.contact,            heyf_tmp.bill_status,            heyf_tmp.bill_code,            @rownum:=@rownum + 1,            if(@pdept = heyf_tmp.contact, @rank:=@rank + 1, @rank:=1) as rank,            @pdept:=heyf_tmp.contact    from        (select     t1.merchantId,    t2.NameCn,    t1.send_date,    t1.deliver_name,    t1.deliver_address,    concat(t1.deliver_phone,',',t1.deliver_mobile) as 'contact',    t1.bill_status,    t1.bill_codefrom    bill_master t1left join     sys_merchant_master t2 on t1.merchantId = t2.merchantIdwhere    bill_status != 10order by deliver_phone,deliver_mobile) heyf_tmp, (select @rownum:=0, @pdept:=null, @rank:=0) a) result;

实现结果截图：