Best way to select distinct values based on another column?

Question

I have a table with three columns: id (NUMBER), data_dt (DATE), and data_value (NUMBER).
There is a primary key on id and data_dt.
I want to select the record with the latest data_dt for each unique id.
What is the best way to do this?
I have three different methods, but there may be something I am missing.
First:
SELECT *
FROM
  SELECT id, data_dt, data_value,
         FIRST_VALUE(data_dt)
         OVER (PARTITION BY id ORDER BY data_dt DESC) AS last_data_dt
  FROM the_table
WHERE data_dt = last_data_dt;(I use ORDER BY...DESC instead of just ORDER BY so I don't need the ROWS BETWEEN clause)
Second:
SELECT t1.*
FROM the_table t1
JOIN
  SELECT id, MAX(data_dt) AS last_data_dt
  FROM the_table
  GROUP BY id
) t2 ON (t2.id = t1.id AND t2.data_dt = t1.data_dt);Third:
SELECT t1.*
FROM the_table t1
WHERE t1.data_dt =
  SELECT MAX(t2.data_dt)
  FROM the_table t2
  WHERE t2.id = t1.id
);-- Don

Answer 1

Hi,
There are more possible scenario's, for example:
select t1.*
from   the_table t1
where not exists ( select null
                   from   the_table t2
                   and    t2.data_dt > t1.data_dt
What is the best way to do this?Only you can tell:
Test all scenario's, check the execution plans, set timing on and pick the best/fastest one ;-)
If it's not clear, please post the execution plans here.