Update last row in group with data from first row in group - mysql

Question

I'm currently in the process of converting data from one structure to another, and in the process I have to take a status id from the first entry in the group and apply it to the last entry in that same group. I am able to target and update the last item in the group just fine when using a hard-coded value, but I'm hitting a wall when trying to use the status_id from the first entry. Here is an example of the data structure.
-----------------------------------------------------------
| id | ticket_id | status_id | new_status_id | created_at |
-----------------------------------------------------------
| 1 | 10 | NULL | 3 | 2018-06-20 |
| 2 | 10 | 1 | 1 | 2018-06-22 |
| 3 | 10 | 1 | 1 | 2018-06-23 |
| 4 | 10 | 1 | 1 | 2018-06-26 |
-----------------------------------------------------------
So the idea would be to take the new_status_id of ID 1 and apply it to the same field for ID 4.
Here is the query that works when using a hard-coded value
UPDATE Communications_History as ch
JOIN
(
SELECT communication_id, MAX(created_at) max_time, new_status_id
FROM Communications_History
GROUP BY communication_id
) ch2
ON ch.communication_id = ch2.communication_id AND ch.created_at = ch2.max_time
SET ch.new_status_id = 3
But when I use the following query, I get Unknown column ch.communication_id in where clause
UPDATE Communications_History as ch
JOIN
(
SELECT communication_id, MAX(created_at) max_time, new_status_id
FROM Communications_History
GROUP BY communication_id
) ch2
ON ch.communication_id = ch2.communication_id AND ch.created_at = ch2.max_time
SET ch.new_status_id = (
SELECT nsi FROM
(
SELECT new_status_id FROM Communications_History WHERE communication_id = ch.communication_id AND status_id IS NULL
) as ch3
)
Thanks!

Answer 1

So I just figured it out using variables. It turns out the original "solution" only worked when there was one ticket's worth of history in the table, but when all the data was imported, it no longer worked. However, this tweak did seem to fix the issue.
UPDATE Communications_History as ch
JOIN
(
SELECT communication_id, MAX(created_at) max_time, new_status_id
FROM Communications_History
GROUP BY communication_id
) ch2
ON ch.communication_id = ch2.communication_id AND ch.created_at = ch2.max_time
SET ch.new_status_id = ch2.new_status_id;