我不确定获得百分位数。我正在使用基于下面select nth percentile from mysql 的子查询，但我不太确定我是否已正确修改它。我的回答的重点在于子查询的组合。
随着表大小的增加，以下查询会很慢并且呈指数级变慢，但它应该可以满足您的需求：
SELECT p10.Date, Pct10, Pct90
FROM (
SELECT Date, count(Value) AS Pct10
FROM mydata
GROUP BY Date, Value
ORDER BY ABS(0.1-(count(Value)/(select count(*) from mydata)))
LIMIT 1) AS p10
INNER JOIN (
SELECT Date, count(Value) AS Pct9
FROM mydata
GROUP BY Date, Value
ORDER BY ABS(0.9-(count(Value)/(select count(*) from mydata)))
LIMIT 1) AS p90 ON p10.Date = p90.Date
GROUP BY p1.Date
这是我的第二个想法。如果它有效，它将比我列出的第一个更快、更高效，但对于较大的表来说仍然相当慢。
SELECT p10.Date, count(Value) AS Pct10, Pct90
FROM mydata p10
INNER JOIN (
SELECT Date, count(Value) AS Pct90
FROM mydata
GROUP BY Date, Value
ORDER BY ABS(0.9-(count(Value)/(select count(*) from mydata)))
LIMIT 1) AS p90 ON p10.Date = p90.Date
GROUP BY Date, Value
ORDER BY ABS(0.1-(count(Value)/(select count(*) from mydata)))
LIMIT 1
编辑
好的，头脑风暴时间。鉴于这是一个日期百分位数的子查询（我什至不确定它是如何工作的）：
SELECT Date, count(Value) AS Pct90
FROM mydata
WHERE Date = ?
GROUP BY Value
ORDER BY ABS(0.9-(count(Value)/(select count(*) from mydata WHERE Date = ?)))
LIMIT 1
然后让我们尝试修复 ORDER BY：
SELECT Date, count(Value) as Pct90
FROM mydata
INNER JOIN (SELECT Date, COUNT(*) AS DateTotal FROM mydata GROUP BY Date) AS d
ON d.Date = mydata.Date
GROUP BY Date, Value
ORDER BY (ABS(0.9-(COUNT(Value)/d.DateTotal)))
LIMIT 1
如果您在我之前的示例中使用此模式，也许它会起作用。
编辑 2
所以，我们又来了，因为我们不能使用 LIMIT 1（我之前应该意识到这一点）。我实际上在我自己的数据库上测试了以下内容（希望我将所有字段和表名改回它们应该的样子！），它似乎工作。您必须为 p10 再次执行此操作并将两者结合起来。
--- removed due to typos ---
编辑 3
我在编辑 2 中发现了一些错误，因此我将其删除。这是整个百分比查询。据我所知，此查询适用于我的数据库（使用不同的字段和表）。
SELECT n.Date, n.Pct AS Pct10, n.Value AS Pct10Value, q.Pct AS Pct90, q.Value AS Pct90Value FROM (
SELECT p.Date, p.Pct, p.Value, m.Selector FROM (
SELECT mydata.Date, Value, COUNT(Value) as Pct, (ABS(0.1-(COUNT(Value)/d.DateTotal))) AS Abs10
FROM mydata
INNER JOIN (SELECT Date, COUNT(*) AS DateTotal FROM mydata GROUP BY Date) AS d
ON d.Date = mydata.Date
GROUP BY Date, Value
) p
INNER JOIN (
SELECT Date, MIN(Abs10) AS Selector FROM (
SELECT mydata.Date, Value, COUNT(Value) as Pct, (ABS(0.1-(COUNT(Value)/d.DateTotal))) AS Abs10
FROM mydata
INNER JOIN (SELECT Date, COUNT(*) AS DateTotal FROM mydata GROUP BY Date) AS d
ON d.Date = mydata.Date
GROUP BY Date, Value
) x GROUP BY Date
) AS m ON m.Selector = p.Abs10
GROUP BY p.Date) n
INNER JOIN (
SELECT p.Date, p.Pct, p.Value, m.Selector FROM (
SELECT mydata.Date, Value, COUNT(Value) as Pct, (ABS(0.9-(COUNT(Value)/d.DateTotal))) AS Abs90
FROM mydata
INNER JOIN (SELECT Date, COUNT(*) AS DateTotal FROM mydata GROUP BY Date) AS d
ON d.Date = mydata.Date
GROUP BY Date, Value
) p
INNER JOIN (
SELECT Date, MIN(Abs90) AS Selector FROM (
SELECT mydata.Date, Value, COUNT(Value) as Pct, (ABS(0.9-(COUNT(Value)/d.DateTotal))) AS Abs90
FROM mydata
INNER JOIN (SELECT Date, COUNT(*) AS DateTotal FROM mydata GROUP BY Date) AS d
ON d.Date = mydata.Date
GROUP BY Date, Value
) x GROUP BY Date
) AS m ON m.Selector = p.Abs90
GROUP BY p.Date) q ON q.Date = n.Date