Question

I am learning MySQL with a sample database.
I have a table “production” where with columns: cd_code, company and year.
I would like to find which company has produced the most cds.

This:

select company, count(cd_code) from production group by company;

Which gives me the companies and how many CDs each has released.
Now from that table with columns (as appeared) company, count(code_cd)
I want to print the company which has the most CDs.
So I want the max of the 2nd column of the 2nd table.

What I am trying is this:

select max(res.cd_code) from (select company, count(cd_code) from production group by company) as res;

And I am getting error 1054:

Unknown column ‘cd_code’ in ‘field list’

What can I do?

Thank you for your time!

Answer 1

You are selecting company, count(cd_code) in res and hence there is no cd_code in res.

If you want to access the count of the cd_code from res, then try below:

          SELECT max(res.COUNT_CODE) 
          FROM
             (SELECT company, count(cd_code) AS COUNT_CODE 
              FROM production 
              GROUP BY company) as res;