Question

这是我的结果表：

+------------+--------+--------+
| tournament | player | Points |
+------------+--------+--------+
| 1          | Bob    | 9      |
| 1          | Jeff   | 2      |
| 1          | Steve  | 1      |
| 2          | Bob    | 5      |
| 2          | Jeff   | 3      |
| 2          | Steve  | 8      |
| 2          | Paul   | 4      |
| 3          | Bob    | 9      |
| 3          | Jeff   | 3      |
| 3          | Steve  | 2      |
+------------+--------+--------+

我想了解一名球员赢得锦标赛的次数。因此，我应该得到这些结果：

Bob: 2
Steve: 1
Jeff: 0
Paul: 0

我该怎么做？

Answer 1

在这里（从内到外阅读评论）：

select /*3. and finally we left join the original table to get all names and display the number of wins again*/
outerq.player,
coalesce(subq.wins, 0) as wins
from
Table1 outerq
left join (
  select /*2. Now we determine how much tournaments each player won*/
  ot.player,
  count(*) as wins
  from (
    select /*1. First we determine the winners per tournament here*/
    *
    from
    Table1 t
    where Points = (select max(Points) from Table1 st where st.tournament = t.tournament)
) ot
group by ot.player
) subq on outerq.player = subq.player
group by outerq.player
order by wins desc

看到它在sqlfiddle

MYSQL计数行最大值

1 个答案: