Question

我想获取一个给出主题最大正确答案的用户ID。以下是表结构。

id user_id question_id answered  paper
 1  1       1           0         sub1
 2  2       1           1         sub1
 3  3       1           1         sub1
 4  1       2           1         sub1 
 5  2       2           1         sub1
 6  3       2           0         sub1

我尝试使用sql来获取结果，但是无法弄清楚如何在这个sql中将“2”作为动态

SELECT `user_id` FROM `table` 
WHERE `answered` =1 GROUP BY `paper` 
HAVING Count( `answered` ) >2

得到了答案

select `user_id` FROM table 
where answered = 1 GROUP BY paper,user_id 
HAVING Count(answered) > = (SELECT count( * ) AS count FROM table
WHERE answered =1GROUP BY paper,user_id ORDER BY count DESC Limit 1)

Answer 1

您可以尝试使用这样的动态SQL：

mysql> PREPARE stmt FROM 
    -> 'SELECT `user_id` FROM `table`
    -> WHERE `answered` =1 GROUP BY `paper`
    -> HAVING Count( `answered` ) > ?'

;
Query OK, 0 rows affected (0.00 sec)
Statement prepared
mysql> EXECUTE stmt 
    -> USING @num

最后

mysql> DEALLOCATE PREPARE stmt;

另一个选项是创建一个存储过程，您可以将数字（例如2）作为输入参数传递。

Answer 2

试试这个

    SELECT COUNT(answered) AS answers, user_id FROM `table` WHERE answered=1 GROUP BY user_id ORDER BY answers DESC LIMIT 1, 1

检索给出最大正确答案的用户名

2 个答案: