create or replace function get_doctor_groups(cnum in staff_vs_group.EMP_NO%type)
return staff_vs_group.group_class%type as cclass staff_vs_group.group_class%type;
begin
select distinct group_class
into cclass
from staff_vs_group , staff_dict
where staff_vs_group.emp_no = staff_dict.emp_no and rownum=1;
---加上rownum=1就可以了,不加则报出01422的错误，为什么？
return (cclass);
end;

Error Id: ORA-01422

Title: exact fetch returns more than requested number of rows

Description:

exact fetch returns more than requested number of rows

Action:

Rewrite the query or change number of rows requested

Cause:

The number specified in exact fetch is less than the rows returned.

-- 来自：