Question

Okay, another SQL question. What I am trying to achieve is to show by company, which courses their employees have been to, and from there, which is the most popular for each company.
Currently, this is what I have:

SELECT a.corporatename, e.course_title, b.studentID
FROM corporate a
JOIN students b ON a.corporateID = b.corporateID
JOIN studentcoursedetails c ON b.studentID = c.studentID
JOIN classdetails d ON c.classdetailID = d.classdetailID
JOIN course e ON d.courseID = e.courseID
WHERE b.corporateID != ‘0’
ORDER BY a.corporatename, e.course_title

This gives me something along these lines:

corporatename—————————–course_title———————————studentID
Deutsche Lufthansa AG Berlin—–Airline Security Operations———5
Deutsche Lufthansa AG Berlin—–Airline Security Operations———6
Deutsche Lufthansa AG Berlin—–Airline Security Operations———5
Deutsche Lufthansa AG Berlin—–Workshop on Crisis Management——6
Deutsche Lufthansa AG Berlin—–Workshop on Crisis Management——7
Korean Air Lines Co., Ltd———-Airline Security Operations———8

From the above, we can see that Lufthansa has sent it’s employees to 2 courses so far. Even though studentID 5 has been to a particular course twice, because he flunked the first try, it is recorded as 2 entries.

What I hope to attain is this:

Deutsche Lufthansa AG Berlin—–Airline Security Operations———3
Deutsche Lufthansa AG Berlin—–Workshop on Crisis Management——2
Korean Air Lines Co., Ltd———-Airline Security Operations———1

I tried to use this code:

SELECT a.corporatename, e.course_title, count( DISTINCT b.studentID ) AS total
FROM corporate a
JOIN students b ON a.corporateID = b.corporateID
JOIN studentcoursedetails c ON b.studentID = c.studentID
JOIN classdetails d ON c.classdetailID = d.classdetailID
JOIN course e ON d.courseID = e.courseID
WHERE b.corporateID != ‘0’
GROUP BY a.corporatename
ORDER BY a.corporatename, e.course_title

But what I got:

corporatename—————————–course_title———————————total
Deutsche Lufthansa AG Berlin—–Workshop on Crisis Management——3
Korean Air Lines Co., Ltd———-Airline Security Operations———1

it shows me the most popular, yes, but I’d like to be able to compare all ranks.
I’d appreciate any help on this.

Thanks to bluish, a simple solution.

SELECT a.corporatename, e.course_title, count( b.studentID ) AS total
FROM corporate a
JOIN students b ON a.corporateID = b.corporateID
JOIN studentcoursedetails c ON b.studentID = c.studentID
JOIN classdetails d ON c.classdetailID = d.classdetailID
JOIN course e ON d.courseID = e.courseID
WHERE b.corporateID != ‘0’
GROUP BY a.corporatename , e.course_title
ORDER BY a.corporatename, e.course_title

I removed the DISTINCT because I need to collect data of all enrollments, not each unique user. Thanks.

Answer 1

Try to add also e.course_title in the GROUP BY:

SELECT a.corporatename, e.course_title, count( DISTINCT b.studentID ) AS total
FROM corporate a
JOIN students b ON a.corporateID = b.corporateID
JOIN studentcoursedetails c ON b.studentID = c.studentID
JOIN classdetails d ON c.classdetailID = d.classdetailID
JOIN course e ON d.courseID = e.courseID
WHERE b.corporateID != '0'
GROUP BY a.corporatename, e.course_title
ORDER BY a.corporatename, e.course_title