在低版本的MySQL库中如何实现自增排序的查询

在低版本的MySQL中，要实现自增排序的查询，你可以利用变量`@row_number`来模拟每个分组后的排名。由于你提到的是三个科目的排序，所以可以在每个子查询中添加一个递增的变量。这里是如何操作的：

1. 定义一个全局变量（如果尚未定义）[^1]:

   SET @row_number := 0;

2. 对于每个科目，编写一个子查询，结合当前得分和排名:

   SELECT s.*, @row_number := @row_number + 1 as rank
   FROM score s
   WHERE c_id IN ('01', '02', '03')
   ORDER BY s_score DESC

3. 使用UNION ALL合并三个子查询的结果:

   (
   SELECT * FROM (
       SELECT s.*, @row_number := @row_number + 1 as rank
       FROM score s
       WHERE c_id = '01'
       ORDER BY s_score DESC
   ) as subquery1
   )
   UNION ALL
   (
   SELECT * FROM (
       SELECT s.*, @row_number := @row_number + 1 as rank
       FROM score s
       WHERE c_id = '02'
       ORDER BY s_score DESC
   ) as subquery2
   )
   UNION ALL
   (
   SELECT * FROM (
       SELECT s.*, @row_number := @row_number + 1 as rank
       FROM score s
       WHERE c_id = '03'
       ORDER BY s_score DESC
   ) as subquery3
   );

这样，你会得到每个学生在对应科目中的排名。