如何在PostgreSQL中选择最大计数

我在PostgreSQL中有一个具有以下模式的表：

Category    |   Type 
------------+---------
A           |   0 
C           |   11 
B           |   5 
D           |   1 
D           |   0 
F           |   2   
E           |   11 
E           |   9 
.           |   . 
.           |   .

如何选择类型的类别最大出现次数？以下是我的全部：

SELECT 
    category, 
    type, 
    COUNT(*)
FROM 
    table
GROUP BY 
    category, 
    type
ORDER BY 
    category, 
    count 
    DESC

我的预期结果如下：

类别|计数 ----+----+---

A | 0 | 5

B | 5 | 30

C | 2 | 20

D | 3 | 10

---

这是每个类别中出现次数最多的类型，具有该类型的计数

选择类别，最大发生率 从中选择t.category作为类别，从表t中计算*作为发生

SELECT 
    category, 
    type, 
    COUNT(*)
FROM 
    table
GROUP BY 
    category, 
    type
HAVING 
    COUNT(*) = (SELECT MAX(C) FROM (SELECT COUNT(*) AS C FROM A GROUP BY A) AS Q)

编辑： 我向读者道歉

COUNT(*) = (SELECT MAX(COUNT(*)) FROM table GROUP BY category,type) 

是ORACLE版本，postgresql版本是：

COUNT(*) = (SELECT MAX(C) FROM (SELECT COUNT(*) AS C FROM A GROUP BY A) AS Q)

---

如果我理解正确，您可以使用窗口功能：

SELECT category, type, cnt
FROM (SELECT category, type, COUNT(*) as cnt,
             ROW_NUMBER() OVER (PARTITION BY type ORDER BY COUNT(*) DESC) as seqnum
      FROM table
      GROUP BY category, type
     ) ct
WHERE seqnum = 1;

---

您可以使用以下查询：

SELECT category, type, cnt
FROM (
   SELECT category, type, cnt,
          RANK() OVER (PARTITION BY category 
                       ORDER BY cnt DESC) AS rn
   FROM (
      SELECT category, type, COUNT(type) AS cnt
      FROM mytable
      GROUP BY category, type ) t
) s
WHERE s.rn = 1

上面的查询使用OP中发布的您自己的查询，并对其应用RANK windowed函数。使用秩，我们可以指定来自初始查询的所有记录具有最大的COUNTtype值

注意：如果有多个类型具有特定类别的最大出现次数，则作为使用RANK的结果，上述查询将返回所有类型

---

将列名放在countcol\u name中您可以在您的问题中也包括预期的结果吗？这会导致聚合函数调用不能嵌套到MAXCOUNT中*

SELECT 
    category, 
    type, 
    COUNT(*) AS count
FROM 
    table
GROUP BY 
    category, 
    type
ORDER BY 
    category ASC