Question

我需要一个SQL，我得到的ID比其他的更多......但我需要id而不是计算它创建id的频率......

post    | id 
==============
hello   | 2
guys    | 1
how     | 2
are     | 2

它应该给我“2”。

感谢您的帮助。

Answer 1

SELECT COUNT(*) AS cnt, id
FROM <table>
GROUP BY id
ORDER BY cnt DESC
LIMIT 1

Answer 2

你正在寻找的是什么叫做MODE，我做了类似的事情 Is there a simpler way to find MODE(S) of some values in MySQL

对于有多于1种模式的情况（例如，id 2出现3次而id 1也出现3次）（sqlFiddle）您可以使用以下查询之一

这个将以逗号分隔列表的形式返回id 1和2（当然，您必须用实际的表名替换yourTable）

SELECT GROUP_CONCAT(CASE WHEN occurs=@maxoccurs THEN value ELSE NULL END) as modes 
FROM 
    (SELECT value,occurs,@maxoccurs:=GREATEST(@maxoccurs,occurs) as maxoccurs
     FROM (SELECT id as value,count(*) as occurs
           FROM yourTable
           GROUP BY id)T1,(SELECT @maxoccurs:=0)mo
    )T2;

这个将返回id 1和2作为2个单独的行

SELECT value as id FROM  
  (SELECT value,occurs,@maxoccurs as maxoccurs
  FROM 
    (SELECT value,occurs,@maxoccurs:=GREATEST(@maxoccurs,occurs) as maxoccurs
     FROM (SELECT id as value,count(*) as occurs
           FROM yourTable
           GROUP BY id)T1,(SELECT @maxoccurs:=0)mo
     )T2
  )T3
WHERE occurs = maxoccurs

SQL - 经常出现的值

2 个答案: