Mysql query problem

Question

I have a problem with my mysql query.

My database:

sections
id
section_name

grades
id
user_id
section_id
date
grade

I want my data

Answer 1

If I get this right you want the latest grade per section. This cannot be done simply with MySQL.

You'd need a window function or a sequence generator, neither of which are available in MySQL. There is a workaround using variables, however. See this question for a similar use-case:

MySQL query: Using UNION and getting row number as part of SELECT

Additional background information here:

SQL/mysql - Select distinct/UNIQUE but return all columns?

What you'll likely end up doing is a big nested query that will look like this:

select t.*
from (select @rownum := @rownum + 1 rownum,
             t.*
      from (select *
              from grades join sections on sections.id = grades.section_id 
             where user_id=$id order by grades.date desc
           ) t,
           (select @rownum := 0) r
      ) t
where t.rownum = 1