How a function in Oracle returns a result set

In Oracle, it is sometimes used to return a result set with a function, and here is the demo:

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create or replace type t_test as object(id integer,create_time date,object_name varchar2(60));create or replace type t_test_table as table of t_test;

1. Using an array of methods

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create or replace function f_test(n in number default null)return t_test_table asv_test t_test_table := t_test_table();beginfor i in 1 .. n loopv_test.extend();v_test(v_test.count) := t_test(i, sysdate, ‘name‘ || i);end loop;return v_test;end f_test;/SQL> select * from table(f_test(5));ID CREATE_TIME OBJECT_NAME-------- -------------- -------------1 07-4月 -15 name12 07-4月 -15 name23 07-4月 -15 name34 07-4月 -15 name45 07-4月 -15 name5

2. Using the pipe function

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create or replace function f_test_pipe(n in number default null)return t_test_tablePIPELINED asv_test t_test_table := t_test_table();beginfor i in 1 .. nvl(n, 100) looppipe row(t_test(i, sysdate, ‘name‘ || i));end loop;return;end f_test_pipe;/SQL> select * from table(f_test_pipe(5));ID CREATE_TIME OBJECT_NAME---------- -------------- ----------------1 07-4月 -15 mc12 07-4月 -15 mc23 07-4月 -15 mc34 07-4月 -15 mc45 07-4月 -15 mc5

How a function in Oracle returns a result set