distinct對某些選擇字段不起作用

Question

我有以下查詢以從多個表中進行選擇。

select distinct s.playerId PlayerID, h.name TeamName, 
    m.firstname FirstName, m.lastname LastName, h.year Year 
from scoringnew s 
join 
(select max(s.pts) pts,s.tmid from scoringnew s group by s.tmid) t 
on s.tmid = t.tmid and s.pts = t.pts 
join master m on (m.playerId = s.playerId) 
join ice_hockey_teams_new h on (h.tmid = s.tmid); 

結果正確顯示不同PlayerID。但是，如果我添加上選擇更多的列會顯示類似下面重複PlayerID：

select distinct s.playerId PlayerID, h.name TeamName, 
    m.firstname FirstName, m.lastname LastName, h.year Year, s.pts Points 
from scoringnew s 
join 
(select max(s.pts) pts,s.tmid from scoringnew s group by s.tmid) t 
on s.tmid = t.tmid and s.pts = t.pts 
join master m on (m.playerId = s.playerId) 
join ice_hockey_teams_new h on (h.tmid = s.tmid); 

上述查詢之間的唯一不同的是，第二個查詢有一個更選擇字段s.pts Points，其給出了結果集複製PlayerID。 我想知道爲什麼distinct不適用於所有情況。有什麼我誤解了嗎？顯示

重複的行如下：

Answer 1

你不是故意要選擇t.pts？

select distinct s.playerId PlayerID, h.name TeamName, 
m.firstname FirstName, m.lastname LastName,  h.year Year, t.pts Points 
from scoringnew s 
join 
(select max(s.pts) pts,s.tmid from scoringnew s group by s.tmid) t 
on s.tmid = t.tmid 
join master m on (m.playerId = s.playerId) 
join ice_hockey_teams_new h on (h.tmid = s.tmid);