tosha4encko

SELECT reg_num, MAX( date_creation ) FROM YourTable GROUP BY reg_num

id этого объекта получить?

SELECT id, YourTable.reg_num, YourTable.date_creation 
  FROM YourTable INNER JOIN
    ( SELECT reg_num, MAX( date_creation ) AS MaxDate FROM YourTable GROUP BY reg_num ) AS M
      ON M.reg_num = YourTable.reg_num AND M.MaxDate = YourTable.date_creation