SQL字符串中有错误:

• 不是别名计数(*)列

• 在条件不在的情况下没有组2表

尝试此查询:

SELECT activity 
FROM ( SELECT activity, COUNT(*) AS Number FROM FRIENDS GROUP BY activity) AS getActivities
WHERE Number NOT IN (SELECT MIN(Number) FROM (SELECT activity, COUNT(*) AS Number FROM FRIENDS GROUP BY activity )  AS maximum)
AND Number NOT IN (SELECT MAX(Number) FROM (SELECT activity, COUNT(*) AS Number FROM FRIENDS GROUP BY activity) AS minimum)