Question

正如标题中所提到的，我正在努力寻找一个可以显示所有用户的SQL查询＆＃39;昵称（来自用户表），有3个最常见的评级及其评级数，按照在评级表中的出现排序。

表格：

1. Users  
+========+==========+  
| userID | userName |  
+--------+----------+  
|   1    |  User1   |  
|   2    |  User2   |  
|   3    |  User3   |  
|   4    |  User4   |  
|   5    |  User5   |  
|   6    |  User6   |  
+========+==========+


2. Ratings (the rating column is irrelevant)  
+========+========+  
| userID | rating |  
+--------+--------+  
|   1    |   5    |  
|   3    |   4    |  
|   5    |   2    |  
|   1    |   5    |  
|   5    |   3    |  
|   4    |   6    |  
|   2    |   2    |  
|   1    |   4    |  
|   5    |   5    |  
|   2    |   1    |  
|   4    |   3    |  
|   5    |   1    |
+========+========+

查询的结果将是：

User5 4  
User1 3  
User2 2  
User4 2

这是我到目前为止的进展，虽然它显示没有值且未排序的用户，可能不是正确的方法：

SELECT userName  
FROM Users  
WHERE userID  
IN(  
    SELECT userID s  
    FROM Ratings s  
    WHERE (  
        SELECT count( userID )  
        FROM Ratings  
        WHERE userID = s.userID  
        ) >= (  
            SELECT COUNT( userID ) AS number  
            FROM Ratings  
            GROUP BY userID  
            ORDER BY number DESC  
            LIMIT 1  
            OFFSET 3  
    )  
)

我感谢任何帮助，无论是完整的查询还是只是提示。提前谢谢！

Answer 1

SELECT Z.* FROM
  (
    SELECT u.UserName,
           COUNT( * ) AS NoOfOccurences
      FROM Users u
      JOIN 
           Ratings r
        ON u.userID = r.userID
     GROUP BY u.UserName
  ) Z
     ORDER BY Z.NoOfOccurences DESC;

Answer 2

我想我已经解决了，伙计们：

SELECT userName
FROM Users u
WHERE u.userID
IN (
    SELECT userID
    FROM Ratings r
    WHERE (
        SELECT COUNT( userID ) AS number
        FROM Ratings
        GROUP BY userID
        ORDER BY number DESC
        LIMIT 1
        OFFSET 3
    ) <= (
        SELECT count( userID )
        FROM Ratings
        WHERE userID = r.userID
    )
)
ORDER BY (
    SELECT count( userID )
    FROM Ratings
    WHERE userID = u.userID
) DESC

尝试构建一个SQL SELECT查询，显示发生率最高的用户

2 个答案: