Question

我想使用总数和某些条件（例如，exam_Id，class_id，section_id，年份）进行排名。我有许多数据使用不同的exam_Id，class_id，section_id，年份。现在，我想在这些项目（例如exam_Id，class_id，section_id，year）匹配时对它们进行排名。在下面，我给了您一个sql查询，我尝试了一些方法，但是却给出了整个结果。

SELECT id, student_id, total_mark, FIND_IN_SET( total_mark, (
SELECT GROUP_CONCAT( total_mark
ORDER BY total_mark DESC ) 
FROM total_marks )
) AS rank
FROM total_marks

SQL fiddle Link

Answer 1

如果要使用此方法对记录组进行排名，则需要相关的子查询：

SELECT id, student_id, exam_id, class_id, total_mark, section_id, year,
       FIND_IN_SET(total_mark,
                   (SELECT GROUP_CONCAT( total_mark ORDER BY total_mark DESC ) 
                     FROM total_marks tm2
                     WHERE tm2.exam_Id = tm.exam_id AND
                           tm2.class_id = tm.class_id AND
                           tm2.section_id = tm.section_id AND
                           tm2.year = tm.year
                   )
                  ) AS rank
FROM total_marks tm;

Here是db <>小提琴。

请注意，正确的编写方法是使用窗口函数：

SELECT tm.*,
       RANK() OVER (PARTITION BY exam_Id, class_id, section_id, year 
                    ORDER BY total_mark DESC
                   ) as rank
FROM total_marks tm;

此功能是标准SQL，从8.0版开始在MYSQL中可用。

我想使用某些条件进行排名

1 个答案: