oracle table()函式用法

oracle記憶體表在查詢和報表的時候用的比較多，它的速度相對物理表要快幾十倍。

simple example：

1、table()結合陣列：

*/

create or replace type t_test as object(
id integer,
rq date,
mc varchar2(60)
);

create or replace type t_test_table as table of t_test;

create or replace function f_test_array(n in number default null) return t_test_table
as
v_test t_test_table := t_test_table();
begin
for i in 1 .. nvl(n,100) loop
v_test.extend();
v_test(v_test.count) := t_test(i,sysdate,'mc'||i);
end loop;
return v_test;
end f_test_array;
/

select * from table(f_test_array(10));

select * from the(select f_test_array(10) from dual);

/*

2、table()結合PIPELINED函式：

*/

create or replace function f_test_pipe(n in number default null) return t_test_table PIPELINED
as
v_test t_test_table := t_test_table();
begin
for i in 1 .. nvl(n,100) loop
pipe row(t_test(i,sysdate,'mc'||i));
end loop;
return;
end f_test_pipe;
/

select * from table(f_test_pipe(20));

select * from the(select f_test_pipe(20) from dual);

/*

3、table()結合系統包：

*/

create table test (id varchar2(20));
insert into test values('1');
commit;
explain plan for select * from test;
select * from table(dbms_xplan.display);