我有一个查询正在运行。。。不过，我希望能够以特定的方式进行排序/排序。我当前的查询（例如）返回如下日期：

CenterID, OrgName, ID, Relationship, REL_START_YEAR, REL_END_YEAR, Full_Name

(84864, 'Twin Cities Spine Center', '19100', 'Fellow', '1971', '1971', 'Robert B. Winter, MD'),
(84864, 'Twin Cities Spine Center', '19100', 'Founder', '1971', '1972', 'Robert C. Summer, MD'),
(84864, 'Twin Cities Spine Center', '19100', 'Faculty', '1971', '1974', 'Robert D. Spring, MD'),
(84864, 'Twin Cities Spine Center', '19100', 'Fellow', '1972', '1974', 'Robert A. Fall, MD'),
(84864, 'Twin Cities Spine Center', '19100', 'Faculty', '1975', '1976', 'Ginger B. Jones, MD'),
(84864, 'Twin Cities Spine Center', '19100', 'Founder', '1977', '1978', 'Mary F. Johnson, MD'),
(84864, 'Twin Cities Spine Center', '19100', 'Faculty', '1971', '1972', 'Shawn S. Dimmer, MD'),
(84864, 'Twin Cities Spine Center', '19100', 'Fellow', '1978', '1978', 'Scotty B. Raw, MD'),
(84864, 'Twin Cities Spine Center', '19100', 'Fellow', '1978', '1981', 'Lou V. Louis, MD'),
(84864, 'Twin Cities Spine Center', '19100', 'Founder', '1984', '1984', 'Paula L. Davis, MD'),
(84864, 'Twin Cities Spine Center', '19100', 'Fellow', '1981', '1982', 'Nadine H. Ericson, MD');

不过，我想把东西分类/排序/分组
首先是关系栏。。但不仅仅是阿尔法排序。。我想把它列为
创始人第一教员第二研究员第三。。。
然后上面的每一个“组”都按相对的开始年份排序
这让我很接近。。但不是对关系列顺序的粒度控制：

SELECT o.CenterID
     , o.OrgName
     , r.ID
     , r.Relationship
     , r.REL_START_YEAR
     , r.REL_END_YEAR
     , u.ID
     , u.Full_Name 
  FROM genealogy_orgs o
  JOIN genealogy_relations r
    ON r.CenterID = o.CenterID 
  JOIN genealogy_users u
    ON u.ID = r.ID 
 WHERE o.CenterID = 84864
 ORDER 
    BY r.Relationship DESC
     , r.REL_START_YEAR ASC;

为了能够在“关系”列中按唯一顺序进行排序/分组，我在寻找什么？in（）函数的某种用法？