MariaDB 10.5

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CREATE TABLE `tickets` (
  `id`   INT unsigned,
  `name` VARCHAR(50) NOT NULL,
  PRIMARY KEY (`id`)
);
INSERT INTO `tickets` VALUES
(333,'Josephine'),(353,'Jack');
CREATE TABLE `ticket_responses` (
  `id`       INT unsigned NOT NULL AUTO_INCREMENT,
  `ticketId` INT unsigned NOT NULL,
  `time`     DATE NOT NULL,
  PRIMARY KEY (`id`)
);
INSERT INTO `ticket_responses`(`ticketId`,`time`) VALUES
(333,'2020-07-01'), (333,'2020-09-11'), (353,'2020-10-10'),
(353,'2020-07-11'), (353,'2020-07-21'), (353,'2020-09-27');
SELECT id, name, ticketId, time
  FROM
  (
  SELECT @row_num := IF(@id = tr.ticketId, @row_num + 1, 1) AS row_num,
         @id := tr.ticketId, tr.*
    FROM (SELECT @id := 0, @row_num := 0, tr.*, t.name 
            FROM ticket_responses AS tr
            JOIN tickets AS t
              ON tr.ticketId = t.id
           ORDER BY ticketId, time DESC) AS tr
  ) AS tt  
  WHERE tt.row_num = 1           


id
name
ticketId
time


2
Josephine
333
2020-09-11

3
Jack
353
2020-10-10


# with window function #
SELECT id, name, ticketId, time
  FROM 
  ( 
   SELECT ROW_NUMBER() OVER(PARTITION BY tr.ticketId ORDER BY tr.time DESC) AS row_num,
          tr.*, t.name
     FROM tickets AS t
     JOIN ticket_responses AS tr
       ON tr.ticketId = t.id
   ) AS q    
 WHERE row_num = 1


id
name
ticketId
time


2
Josephine
333
2020-09-11

3
Jack
353
2020-10-10