How to extend the query to add 0 in the cell when no activity is performed

Question

I have the following query, it is working fine to show the cricket time played per day. All I need is to show 0 when no cricket is played. At the moment it is skipping those

Answer 1

First You have to generate the Date series with a query like this:

-- Generate 15 past days name from now
set @n:=date(now() + interval 1 day);
select (select @n:= @n - interval 1 day) day_series from users  limit 15;

and then join select with date_series. for null values you can use COALESCE:

SELECT q2.day_series as days , COALESCE(TimePerDay, 0) as TPD from Your_select q1
right join (
    -- select date_series
) as q2
on q1.Timestamp = q2.day_series and .... 

--- final Query based on my understanding from 1st query

set @n:=date(now() + interval 1 day);
SELECT activity
,cast(starttime AS DATE) AS q1_DATE
,COALESCE(SUM(datediff(second, starttime, endtime)) / 60.0, 0) AS TimePerDay
FROM (
    SELECT email
        ,last_update
        ,activity
        ,starttime
        ,endtime
        ,duration AS Totaltime
    FROM users
    WHERE activity = 'cricket'
        AND email = 'abc'
    GROUP BY email
        ,activity
        ,duration
        ,starttime
        ,endtime
        ,last_update
    ) q1
RIGHT JOIN (
    SELECT (
            SELECT @n: = @n - interval 1 day
            ) day_series
    FROM users limit 15
    ) q2 ON q1.q1_DATE = q2.day_series
WHERE starttime >= dateadd(day, - 15, last_update)
GROUP BY activity
    ,cast(starttime AS DATE);