Friday, August 22, 2014

Ref Cursor in Oracle PL/SQL

A REF CURSOR is basically a data type.  A variable created based on such a data type is generally called a cursor variable.  A cursor variable can be associated with different queries at run-time.

Let us start with a small sub-program as follows:



%ROWTYPE with REF CURSOR

In the previous section, I retrieved only one column (ename) of information using REF CURSOR.  Now I would like to retrieve more than one column (or entire row) of information using the same.  Let us consider the following example:

declare
  type r_cursor is REF CURSOR;
  c_emp r_cursor;
  er emp%rowtype;
begin
  open c_emp for select * from emp;
  loop
      fetch c_emp into er;
      exit when c_emp%notfound;
      dbms_output.put_line(er.ename || ' - ' || er.sal);
  end loop;
  close c_emp;
end;
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As defined earlier, a REF CURSOR can be associated with more than one SELECT statement at run-time.  Before associating a new SELECT statement, we need to close the CURSOR.  Let us have an example as follows:

declare
  type r_cursor is REF CURSOR;
  c_emp r_cursor;
  type rec_emp is record
  (
    name  varchar2(20),
    sal   number(6)
  );
  er rec_emp;
begin
  open c_emp for select ename,sal from emp where deptno = 10;
  dbms_output.put_line('Department: 10');
  dbms_output.put_line('--------------');
  loop
      fetch c_emp into er;
      exit when c_emp%notfound;
      dbms_output.put_line(er.name || ' - ' || er.sal);
  end loop;
  close c_emp;
  open c_emp for select ename,sal from emp where deptno = 20;
  dbms_output.put_line('Department: 20');
  dbms_output.put_line('--------------');
  loop
      fetch c_emp into er;
      exit when c_emp%notfound;
      dbms_output.put_line(er.name || ' - ' || er.sal);
  end loop;
  close c_emp;
end;

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