利用函数返回oracle对象表的三种方法

create or replace type t_test as object(
 EMPNO  NUMBER(4),
 ENAME  VARCHAR2(10),
 JOB   VARCHAR2(9),
 SAL   NUMBER(7,2)
);

create or replace type t_test_table as table of t_test;

create or replace function f_test_array(v_deptno in number default null)
return t_test_table
is 
v_test t_test_table := t_test_table();
cursor cur is select empno, ename, job, sal from emp where deptno = v_deptno;
begin
for c in cur loop
v_test.extend();
v_test(v_test.count) := t_test(c.empno, c.ename, c.job, c.sal);
end loop;
return v_test;
end;

create or replace function f_test_pipe(v_deptno in number default null)
return t_test_table PIPELINED 
is
v_test t_test_table := t_test_table();
cursor cur is select empno, ename, job, sal from emp where deptno = v_deptno;
begin 
for c in cur loop
pipe row(t_test(c.empno, c.ename, c.job, c.sal)); 
end loop; 
return; 
end;

create or replace function f_test_collect(v_deptno in number default null)
return t_test_table
is 
v_test t_test_table := t_test_table();
begin
select t_test(empno, ename, job, sal) bulk collect into v_test from emp where deptno = v_deptno;
return v_test;
end;

select  from table(f_test_pipe(30));
select  from table(f_test_array(30));
select  from table(f_test_collect(30));