mysql - 使用子查询返回的结果对 SQL 查询进行排序

Question

嘿，我正在尝试使用从子查询返回的结果来订购 SQL 查询，即

SELECT tb1.stud_id , tb1.stud_name , (SELECT sum(score) FROM scores WHERE student_id = tb1.
student) AS total_marks 
FROM Students_info AS tb1
GROUP BY tb1.stud_id , tb1.stud_name
ORDER BY total_marks DESC

我也试过

ORDER BY (SELECT sum(score) FROM scores WHERE student_id = tb1.student) DESC

对此提供帮助将不胜感激。

Answer 1

我对您的查询感到困惑，您订购的 select 语句将为每个学生返回相同的结果，因为它与 students_info 表无关。

我假设你想要这样的东西：

SELECT tb1.stud_id , tb1.stud_name , SUM(tb2.score) AS total_marks
FROM Students_info AS tb1
LEFT JOIN scores AS tb2
    ON tb1.stud_id = tb2.student_id
GROUP BY tb1.stud_id , tb1.stud_name
ORDER BY total_marks DESC

Answer 2

我发现您的查询没有任何问题。试试这个 sql。它会起作用的。

SELECT tb1.stud_id , tb1.stud_name , sum(tb2.score) AS total_marks 
FROM Students_info AS tb1
LEFT JOIN scores AS tb2
ON tb1.student_id=tb2.student_id
GROUP BY tb1.stud_id , tb1.stud_name
ORDER BY sum(tb2.score) DESC