Question

我编写以下MySQL命令来获取学生的分数总和并对其进行相应排名。

SELECT student_id, thescore, @rownum:=@rownum + 1 AS rankstudent 
FROM
(
    SELECT student_id, SUM(score) AS thescore
    FROM school_ranking
    WHERE school like '%Standard6%' and student_id <> ''
    GROUP BY student_id
    ORDER BY thescore DESC

) Sub1 
CROSS JOIN (SELECT @rownum:=0) Sub2

结果如下：

student_id   thescore    rankstudent
J007766      5739            1 
J007625      5159            2 
J007629      5158            3 
J007713      4460            4 
J007690      4384            5

我的问题是如何获得特定学生的排名？例如，如何获得ID为＆＃39; J007625＆＃39;

的学生的等级？

Answer 1

class Something {
public:
    void start() {
        this->task_ = std::thread(&Something::someTask, this);
        this->isRunning_ = true;
        this->task_.detach(); // I read detach will stop it from hanging
    }

    void stop() {
        this->isRunning = false;
    }

    ~Something() {
         this->stop();
    }        

private:
    std::atomic<bool> isRunning_;
    std::thread task_;
    void someTask()
    {
        while(this->isRunning_) {
            // do something forever
        }
    }
};

Something whatever;
whatever.start();

如何根据分数总和获得特定用户的排名？

1 个答案: