SQL实现分组排序和组内排序（相同分数并列排名）

创建数据表

CREATE TABLE `heyf_t10` (
  `empid` int(11) DEFAULT NULL,
  `deptid` int(11) DEFAULT NULL,
  `salary` decimal(10,2) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8

插入数据

INSERT INTO `heyf_t10` VALUES ('1', '10', '5500.00');
INSERT INTO `heyf_t10` VALUES ('2', '10', '4500.00');
INSERT INTO `heyf_t10` VALUES ('3', '20', '1900.00');
INSERT INTO `heyf_t10` VALUES ('4', '20', '4800.00');
INSERT INTO `heyf_t10` VALUES ('5', '40', '14500.00');
INSERT INTO `heyf_t10` VALUES ('6', '40', '14500.00');
INSERT INTO `heyf_t10` VALUES ('7', '40', '44500.00');
INSERT INTO `heyf_t10` VALUES ('8', '50', '6500.00');
INSERT INTO `heyf_t10` VALUES ('9', '50', '7500.00');
INSERT INTO `heyf_t10` VALUES ('10', '40', '14000.00');
INSERT INTO `heyf_t10` VALUES ('11', '40', '14500.00');
INSERT INTO `heyf_t10` VALUES ('12', '40', '14550.00');
INSERT INTO `heyf_t10` VALUES ('13', '40', '14550.00');

实现按照部门分组，salary为排序项

select empid,deptid,salary,rank from ( 
        select heyf_tmp.empid,heyf_tmp.deptid,heyf_tmp.salary,@rownum:=@rownum+1 , 
               if(@pdept=heyf_tmp.deptid AND @salary>=heyf_tmp.salary,@rank:=@rank+1,@rank:=1) as rank1, 
               if(@pdept=heyf_tmp.deptid AND @salary=heyf_tmp.salary,@rank:=@rank-1,@rank) as rank,
               @pdept:=heyf_tmp.deptid,
               @salary:=heyf_tmp.salary
         from (  
               select empid,deptid,salary from heyf_t10 order by deptid asc ,salary desc  
         ) heyf_tmp ,
        (select @rownum :=0 , @pdept := null ,@rank:=0) a 
 ) result ;

运行结果入下：