Question

I want to use single cursor to fetch single record or all records using where condition, e.g. : student is table and sid is an attribute.

I have two cursors,

DECLARE S1 CURSOR FOR SELECT * FROM Student;

and

Declare S2 Cursor for select * from Student where sid=11

My query is on how to combine these two conditions to use only one cursor. I need this as I have two functions m_viewStudent and m_viewallStudents, for this I would like to use only one cursor to display the requested details from table.

so how can I achieve this ?

Answer 1

Try this:

select * 
from student
where sid = 11 
or not exists (select 1 from student where sid = 11)

Here is a sqlfiddle demo

---

UPDATE

If you want to use the same cursor for different functions then you can do it like this:

create package p is

  procedure one_sid(in_sid number);
  procedure all_sid;

end p;
/

create package body p is

  cursor c(p_sid number) is
  select * 
    from student 
   where sid = p_sid or p_sid is null;

  procedure one_sid(in_sid number) is

  begin

   open c(in_sid);

   close c;

  end;

  procedure all_sid is

  begin

   open c(null);

   close c;

  end;

end p;
/