Converting subquery to join assistance - sql

Question

I am my subquery is severely slowing my full query down in MySQL. I'm in the process of converting the original query to work on MySQL as I'm moving away from SQL Server where it has worked wonderfully. MySQL on the other hand isnt too happy. Was wondering if anyone could assist in helping me with a conversion solution to a join as I'm not well versed in joins quite yet. Thanks!
select a.crm_ticket_details_detail,
crm_ticket_created_date,
crm_ticket_id,
crm_ticket_customer_id,
c.crm_assigned_user
from php_crm.crm_ticket,
php_crm.crm_ticket_details a,
php_crm.crm_assigned c
where crm_ticket_resolved_date is null
and crm_ticket_id = a.crm_ticket_details_ticket_id
and a.crm_ticket_details_type = 'issue'
and c.crm_assigned_ticket_id = crm_ticket_id
and c.crm_assigned_id = (select max(d.crm_assigned_id)
from php_crm.crm_assigned d
where d.crm_assigned_ticket_id = crm_ticket_id)

Answer 1

SELECT
details.crm_ticket_details_detail,
CT.crm_ticket_created_date,
CT.crm_ticket_id,
CT.crm_ticket_customer_id,
ASSIGNED.crm_assigned_user
FROM
php_crm.crm_ticket CT (NONAME)
INNER JOIN php_crm.crm_ticket_details DETAILS -- (A)
ON CT.crm_ticket_id = DETAILS.crm_ticket_details_ticket_id
INNER JOIN php_crm.crm_assigned ASSIGNED -- (C)
ON CT.crm_ticket_id = ASSIGNED.crm_assigned_ticket_id
WHERE
crm_ticket_resolved_date IS NULL
AND DETAILS.crm_ticket_details_type = 'issue'
AND
AND ASSIGNED.crm_assigned_id = (SELECT
max(d.crm_assigned_id)
FROM
php_crm.crm_assigned d
WHERE
d.crm_assigned_ticket_id = crm_ticket_id)
I believe that's what you're looking for. I can't speak to whether it will actually improve performance, although it will certainly make it easier to understand. I'm not sure the old style of joins is actually less efficient; just harder to read / easier to make product joins with.
That said, if there are other common keys between the three tables that are being indirectly neutralized in other parts of the logic then that could have a performance impact.
(EDIT: Actually not sure if this was what you're looking for, reread your question and you seem focused on the subquery... I don't see any problems jumping out with that, would need more details to address that.)