获取大部分可用的条目

Question

例如，我有以下数据库条目：

timestamp | value1 | value 2
----------    
1452|5|7
1452|1|6
1452|2|7
1623|1|2
1623|5|6
1623|4|5
1623|4|7
1855|1|2

现在我想要一个sql查询，它只返回值为最大的时间戳的value1。因此它应该只返回时间戳1623及其值。 我第一次考虑计数，但这只会返回可用性的数量，而不是条目。

Answer 1

select *
  from T
 inner join (select timestamp 
               from T 
              group by timestamp 
           order by count(*) desc 
           limit 1) t2
  on T.timestamp = t2.timestamp

• 看到它在sqlfiddle
中正常工作

Answer 2

WITH CTE AS (
  SELECT *, COUNT(timestamps) OVER (PARTITION BY value1, timestamps) AS cnt
  FROM mytable
  ), cte2 as (select *, row_number() over (partition by value1 order by cnt DESC, timestamps) as Rn FROM cte)

SELECT value1, timestamps , cnt FROM CTE2 WHERE Rn = 1;