请问SQL写法，关于Group By

请教SQL写法，关于Group By
select a.FLOW_ID, 
  max(a.FLOW_VER) as FLOW_VER,
  a.FLOW_NAME,
  f.STEP_ID,
  f.STEP_NAME,
  e.NODE_KEY,
  STU.TRACK_RULE_ID,
  STU.TRACK_RULE_NAME  
from SBRM_FLOW a
  left join SBRM_FLOW_NODE_PATH c
  on c.DIA_KEY = a.DIA_KEY
  left join SBRM_FLOW_NODES e
  on e.NODE_KEY = c.FROM_NODE_KEY
  left join SBRM_STEP f
  on f.STEP_KEY = e.STEP_KEY
  left JOIN SBRM_STEP_TRACK_RULE SSTR 
  ON f.STEP_KEY = SSTR.STEP_KEY
  left JOIN SBRM_TRACK_RULE STU
  ON STU.TRACK_RULE_KEY = SSTR.TRACK_RULE_KEY
where a.FLOW_ID = 'F-3P4O1U'
  group by a.FLOW_ID,
  a.FLOW_NAME,
  f.STEP_ID,
  f.STEP_NAME,
  e.NODE_KEY,
  STU.TRACK_RULE_ID,
  STU.TRACK_RULE_NAME
  order by flow_id, NODE_KEY desc
这种写法执行得到的结果是所有FLOW_VER（这是流程的一个版本号）的结果，但其实我只是想要得到一个最大版本号的流程的信息而已，比如，这里有4个版本号，那上面的写法会得出4个版本号的所有结果，但我只想要版本4的结果，请高人指点。

[解决办法]
AND NOT EXISTS(SELECT 1 FROM SBRM_FLOW WHERE FLOW_ID=a.FLOW_ID AND FLOW_VER>a.FLOW_VER)加上條件
去掉group by 
測測看結果是否正確

SQL code

select a.FLOW_ID,   a.FLOW_VER ,  a.FLOW_NAME,  f.STEP_ID,  f.STEP_NAME,  e.NODE_KEY,  STU.TRACK_RULE_ID,  STU.TRACK_RULE_NAME  from SBRM_FLOW a  left join SBRM_FLOW_NODE_PATH c  on c.DIA_KEY = a.DIA_KEY  left join SBRM_FLOW_NODES e  on e.NODE_KEY = c.FROM_NODE_KEY  left join SBRM_STEP f  on f.STEP_KEY = e.STEP_KEY  left JOIN SBRM_STEP_TRACK_RULE SSTR   ON f.STEP_KEY = SSTR.STEP_KEY  left JOIN SBRM_TRACK_RULE STU  ON STU.TRACK_RULE_KEY = SSTR.TRACK_RULE_KEYwhere a.FLOW_ID = 'F-3P4O1U'AND NOT EXISTS(SELECT 1 FROM SBRM_FLOW WHERE FLOW_ID=a.FLOW_ID AND FLOW_VER>a.FLOW_VER)order by flow_id, NODE_KEY DESC
[解决办法]
SQL code
select a.FLOW_ID,    a.FLOW_VER as FLOW_VER,  a.FLOW_NAME,  f.STEP_ID,  f.STEP_NAME,  e.NODE_KEY,  STU.TRACK_RULE_ID,  STU.TRACK_RULE_NAME   from SBRM_FLOW a  left join SBRM_FLOW_NODE_PATH c  on c.DIA_KEY = a.DIA_KEY  left join SBRM_FLOW_NODES e  on e.NODE_KEY = c.FROM_NODE_KEY  left join SBRM_STEP f  on f.STEP_KEY = e.STEP_KEY  left JOIN SBRM_STEP_TRACK_RULE SSTR    ON f.STEP_KEY = SSTR.STEP_KEY  left JOIN SBRM_TRACK_RULE STU  ON STU.TRACK_RULE_KEY = SSTR.TRACK_RULE_KEYwhere a.FLOW_ID = 'F-3P4O1U' anda.FLOW_VER=(select max(FLOW_VER) lastFLOW_VER from SBRM_FLOW a2 where a.FLOW_ID=a2.FLOW_ID)order by flow_id, NODE_KEY desc