按另一个表的结果排序

Question

HI i have skills tables as below

Various user add skills to their profile. Now i want to list all the skills decreasing order of their uses. Like as below

Php(10) , ASP (5) , Perl(1)

Its means 10 user added php as their skill, 5 user ASP etc.

I have stored the skills in user table in skills column with comma separated

Answer 1

Try this:

select id, name
from (
    select *, (select sum(1) from user u where find_in_set(s.id, u.skills)) as cnt
    from skills s
) t
order by cnt desc
-- limit 20

Answer 2

Assuming you have another table/relation to represent user_skills, that contains (for example) user_id and skill_id foreign keys, then you'd want to join this to the skills table and group the results similar to this:

select name, count(skill_id) as ranking
from skills join user_skills on skills.id = user_skills.skill_id
group by name
order by count(skill_id) desc, name asc;

It excludes skills which have not been selected by any users. If you wanted to include those too, change the join to a left join.

Edit: With the original question updated to include the definition of the users table, then perhaps this would suffice. Again you would need a left join to include skills that no users had picked.

select skills.name, count(users.id) as qty
from skills join users 
on locate(concat(',', skills.id, ','), concat(',', users.skills, ',')) > 0
group by skills.name
order by count(users.id) desc, skills.name asc;