Oracle SQL-Error: ORA-00937: not a single-group group function

create or replace view DeptInfo as
select dnumber, dname, AVG(salary), max(salary), min(salary)
from department, employee;

I looked around and tried a combination of Group By's trying to figure this out. Sorry for my pleb-ness, just a measly student.

dnumber and dname are from the department table, while salary is from the employee table.

your question isn't very clear.. what tables are the fields from?

you will need to have sub queries for your 3 fields, since they all require group by clauses

something like

 create or replace view DeptInfo as
 SELECT q1.dnumber, 
        q1.dname, 
        q1.AvgSal,
        q2.MaxSal,
        q3.MinSal
 FROM (SELECT dnumber, dname, AVG(salary) as AvgSal 
       FROM department, employee
       GROUP BY dnumber, dname) q1, 
      (SELECT dnumber, dname, MAX(salary) as MaxSal 
       FROM department, employee
       GROUP BY dnumber, dname) q2, 
      (SELECT dnumber, dname, MIN(salary) as MinSal 
       FROM department, employee
       GROUP BY dnumber, dname) q3
 WHERE q1.dnumber = q2.dnumber AND
       q2.dnumber = q3.dnumber AND
       q1.dname = q2.dname AND
       q2.dname = q3.name

edit: somehow... forgot my group bys...