Combine 2 sql queries into 1 query - mysql

Question

I have 2 queries right now for which I am looking to combine into 1 if possible.
I have open tickets stored in the Tickets_Open table and closed tickets in Tickets_Closed. Both tables have "Date_Requested" and "Date_Completed" columns. I need to count the number of tickets requested and completed each day.
My tickets requested count query is the following:
SELECT SUM(Count) AS TotalOpen, Date FROM(
SELECT COUNT(Ticket_Request_Code) AS Count, Date_Requested AS Date
FROM Tickets_Closed
WHERE Date_Requested >='2018-01-01 00:00:00'
GROUP BY(Date_Requested)
UNION
SELECT COUNT(Work_Request_Code) AS Count, Date_Requested AS Date
FROM Tickets_Open
WHERE Date_Requested >='2018-01-01 00:00:00'
GROUP BY(Date_Requested)
) AS t1 GROUP BY Date ORDER BY `t1`.`Date` DESC
My tickets completed count query is the following:
SELECT COUNT(Ticket_Request_Code) AS CountClosed, Date_Completed AS Date
FROM Tickets_Closed
Where Date_Completed >='2018-01-01 00:00:00'
GROUP BY(Date_Completed)
Both queries return the correct result. For open it returns with the column headings Date and TotalOpen. For close it returns with the column headings Date and CountClosed.
Is it possible to return it with the following column headings Date, TotalOpen, CountClosed.

Answer 1

You can combine these as:
SELECT Date, SUM(isopen) as isopen, SUM(isclose) as isclose
FROM ((SELECT date_requested as date, 1 as isopen, 0 as isclose
FROM Tickets_Closed
WHERE Date_Requested >= '2018-01-01'
) UNION ALL
(SELECT date_requested, 1 as isopen, 0 as isclose
FROM Tickets_Open
WHERE Date_Requested >= '2018-01-01'
) UNION ALL
(SELECT date_closed as date, 0 as isopen, 1 as isclose
FROM Tickets_Closed
WHERE date_closed >= '2018-01-01'
)
) t
GROUP BY Date
ORDER BY Date DESC;
This assumes that Ticket_Request_Code and Work_Request_Code are not NULL. If COUNT() is really being used to check for NULL values, then add the condition to the WHERE clause in each subquery.

Answer 2

This query uses the FULL OUTER JOIN on the Dates as well, but it correctly adds the Open/Closed counts together to give you a TotalOpen Count. This will also handle possible NULL values for cases where you have a day that doesn't close any tickets.
WITH open AS
(
SELECT COUNT(Work_Request_Code) AS OpenCount, Date_Requested AS Date
FROM Tickets_Open
WHERE Date_Requested >='2018-01-01 00:00:00'
GROUP BY(Date_Requested)
)
, close AS
(
SELECT COUNT(Ticket_Request_Code) AS ClosedCount, Date_Requested AS Date
FROM Tickets_Closed
WHERE Date_Requested >='2018-01-01 00:00:00'
GROUP BY(Date_Requested)
)
SELECT
COALESCE(c.Date, o.Date) AS Date
, IFNULL(o.OpenCount, 0) + IFNULL(c.ClosedCount, 0) AS TotalOpen
, IFNULL(c.CountClosed, 0) AS CountClosed
FROM open o
FULL OUTER JOIN closed c ON o.Date = c.Date