对于大容量数据表，更喜欢一些MySql优化技术

我在MySql中遇到了大量数据的查询处理问题。我需要通过join函数将数据提取到四个以上的表中。查询在服务器上运行非常缓慢。

如何优化多个联接查询的处理时间。

我目前正在使用innodb引擎。批量数据表可以。

我有像这样的桌子

这些表中的数据考试、学生、科目、科目测试、科目测试标记、总科目、

我得到了所有学生当前考试的记录。

这之前将通过多个for循环进行处理。连续数据库访问。这就是放慢我进程的原因。如何通过SQL避免这些场景。建议我一些受欢迎的想法。

我对此有些怀疑。表引擎innodb是否正常。索引是否支持此过程？

SELECT `sub`.student_id,
((sum( `sub`.total / `main`.max_total )) / count( sub.id )) *10 AS percent,
GROUP_CONCAT((sub.total / main.max_total) *10 ORDER BY (sub.total / main.max_total) *10 DESC SEPARATOR ',' ) AS marks
FROM 
`cmark_batch` AS `main`
LEFT JOIN `cmark_para_total` AS `sub` 
ON `sub`.mark_batch_id = `main`.id
WHERE main.batch_id =29
AND main.term =4
AND main.subject_id =64
AND main.status = 'A'
GROUP BY student_id
id  select_type     table   type    possible_keys   key     key_len     ref     rows    Extra   
1   SIMPLE  main    ref     search  search  8   const   85  Using index condition; Using where; Using temporary; Using filesort
1   SIMPLE  sub     ref     finder  finder  8   newlive.main.id     14  NULL

SELECT t1.mark_batch_id, t1.id, t1.param_name, t1.max_mark,t2.student, t2.mark
FROM `cmark_parameter` AS t1
LEFT JOIN `cmark_parameter_mark` AS t2 ON t1.id = t2.mark_parameter_id
WHERE t1.mark_batch_id
IN (621,620,623,622)
AND t1.status = 'A'
AND t2.status = 'A'
ORDER BY `t2`.`student` ASC
id  select_type     table   type    possible_keys   key     key_len     ref     rows    Extra   
1   SIMPLE  t2  ALL     NULL    NULL    NULL    NULL    78835   Using where; Using filesort
1   SIMPLE  t1  eq_ref  PRIMARY     PRIMARY     8   newlive.t2.cmark_parameter_id   1   Using where

SELECT t1.student_id, t1.mark_batch_id, t1.total
FROM `cmark_para_total` AS t1
WHERE t1.mark_batch_id
IN (621,620,623,622)
AND t1.status = 'A'
ORDER BY `t1`.`id` ASC

id  select_type     table   type    possible_keys   key     key_len     ref     rows    Extra   
1   SIMPLE  t1  range   finder  finder  8   NULL    111     Using index condition; Using where; Using filesort