Question

I need a little help with the following query. I need to find:

Average number of people per semester of each campus

My table structure is:

• table name – registration
• columns
  • student_id
  • campus
  • year
  • batch
  • semester

and with the help of campus, year, semester and batch I can identify each unique semester. More over my student_id repeats itself in the db.

I did following but it won’t help. So I need some help.

SELECT semester,year,campus
  FROM regestration
  GROUP BY  semester, year, campus
  ORDER BY count(*) desc

Answer 1

Try something like:

SELECT year,campus, AVG(CountOfStudents)
FROM
(
  SELECT semester,year,campus, count(*) as CountOfStudents
  FROM regestration
  GROUP BY  semester, year, campus
) t
GROUP BY  year, campus