Как получить только первое значение в таблице?
С учётом изменения вопроса:SELECT to_char(c.date, 'YYYY-MM-dd HH24:MI:ss') as day,
       c.title, c.email, c.price, c.pages
  FROM (
    SELECT MIN(date) AS date, email FROM customer GROUP BY email
  ) AS t
  JOIN customer AS c ON c.date = t.date AND c.email = d.email
MIN(date) вместе с group by