How select tablename from user_table - sql

Question

I have dinamics tables on my system, it change one number on the name so I do not have a fixed name. I wish to select the lasted table but only the name of the table to make a select to this table.
SELECT * FROM ((SELECT * FROM (select a.tablespace_name || '.' || a.table_name AS TABLE_NAME
from user_tables a
wherE a.tablespace_name='USERNAME'
and a.table_name like '%_DIN'
ORDER BY TABLE_NAME DESC)
WHERE ROWNUM = '1'))
for example.
the table name of
SELECT * FROM (select a.tablespace_name || '.' || a.table_name AS TABLE_NAME
from user_tables a
wherE a.tablespace_name='USERNAME'
and a.table_name like '%_DIN'
ORDER BY TABLE_NAME DESC)
WHERE ROWNUM = '1'
return:
7_DIN
is a name of one table in my tablespace
I want to take this name and make a select of this table.
something like
select * from 7_DIN
All in one statement

Answer 1

Below is code step-by-step, you can test it in this SQLFiddle.
Sample tables used for test:
create table t1(n number)
/
create table t2(n number)
/
create table t13(n number)
/
insert into t1(n) values(1)
/
insert into t2(n) values(2)
/
insert into t13(n) values(13)
/
Declare types used as selection result, same as row type of tables with dynamic names:
create or replace type t_row as object(n number)
/
create or replace type t_rowlist as table of t_row
/
Function which searches for last table and selects data from them into collection, then returns collection as table data:
create or replace function get_last_data return t_rowlist
as
v_table varchar2(30);
v_rows t_rowlist;
begin
select table_name into v_table from (
select * from user_tables where table_name like 'T%'
order by lpad(substr(table_name,2),40,'0') desc
)
where rownum = 1;
execute immediate 'select t_row(n) from '|| v_table
bulk collect into v_rows;
return v_rows;
end;
/
Create view based on function data:
create or replace view last_data_view as
select * from table(get_last_data)
/
This works good only if dynamic tables don't have a big amount of data.
Otherwise it's better to use pipelined functions. To do so, just replace function implementation with code below:
create or replace function get_last_data_pipe
return t_rowlist pipelined
as
v_table varchar2(30);
v_row t_row;
v_cursor sys_refcursor;
begin
select table_name into v_table from (
select * from user_tables where table_name like 'T%'
order by lpad(substr(table_name,2),40,'0') desc
)
where rownum = 1;
open v_cursor for 'select t_row(n) from '|| v_table;
loop
fetch v_cursor into v_row;
exit when v_cursor%notfound;
pipe row(v_row);
end loop;
close v_cursor;
return;
end;
Link to test SQLFiddle.