Order a MySQL query by fastest response time

I have a SQL query:

SELECT number, ResponseTime, TicketCreateTime, 
       round(time_to_sec(timediff(ResponseTime, TicketCreateTime))/60,2) AS FRMins
FROM (SELECT TE.id, T.number, T.ticket_id, TE.thread_id, TE.pid, T.created AS TicketCreateTime, TE.created AS ResponseTime, TE.type, TE.staff_id 
      FROM ost_ticket T INNER JOIN
           ost_thread_entry TE
           ON T.ticket_id = TE.thread_id
      WHERE TE.type = 'N' OR
            TE.type = 'R'  AND TE.id IN (SELECT min(id) FROM ost_thread_entry WHERE type = 'N' OR type = 'R' GROUP BY thread_id)
    ) AS FTRT_tbl; 

number responseTime         TicketCreateTime  FRMins   
120985 2019-09-02 14:28:00  2019-09-02 14:10:00  18.0   
120985 2019-09-02 14:32:00  2019-09-02 14:10:00  22.0  
123490 2019-11-03 16:18:00  2019-11-03 16:17:00   1.0     
123490 2019-11-03 17:18:00  2019-11-03 16:17:00  61.0    

But my goal is to have only one of the number and it should be this one with the lowest FRMins. I tried it in many different ways, but I don’t get it right.

It should look like this one

number responseTime         TicketCreateTime  FRMins  
120985 2019-09-02 14:28:00  2019-09-02 14:10:00  18.0   
123490 2019-11-03 16:18:00  2019-11-03 16:17:00   1.0   

Answer

You can use WHERE EXISTS (SELECT ... GROUP BY ... HAVING) subquery to get the distincts numbers having the lowest FRMins :

Schema (MySQL v5.7)

CREATE TABLE test (
  `number` INTEGER,
  `responseTime` DATETIME,
  `TicketCreateTime` DATETIME,
  `FRMins` INTEGER
);

INSERT INTO test
  (`number`, `responseTime`, `TicketCreateTime`, `FRMins`)
VALUES
  (120985, '2019-09-02 14:28:00', '2019-09-02 14:10:00', 18.0),
  (120985, '2019-09-02 14:32:00', '2019-09-02 14:10:00', 22.0),
  (123490, '2019-11-03 16:18:00', '2019-11-03 16:17:00', 1.0),
  (123490, '2019-11-03 17:18:00', '2019-11-03 16:17:00', 61.0);

---

Query #1

SELECT *
FROM test
WHERE EXISTS
(
  SELECT 1
  FROM test t
  GROUP BY t.number
  HAVING FRMins = MIN(t.FRMins)
);

Output :

| number | responseTime        | TicketCreateTime    | FRMins |
| ------ | ------------------- | ------------------- | ------ |
| 120985 | 2019-09-02 14:28:00 | 2019-09-02 14:10:00 | 18     |
| 123490 | 2019-11-03 16:18:00 | 2019-11-03 16:17:00 | 1      |

---

View on DB Fiddle