How to group by month and return zero if no value for certain month?

Question

This is my mysql income table.

+----+------------------+---------------------------+------------+---------+
| id | title            | description               | date       | amount  |
+----+------------------+---------------------------+------------+---------+
|  1 | Vehicle sales up | From new sale up          | 2016-09-09 | 9999.99 |
|  2 | Jem 2 Sales      | From rathnapura store     | 2016-05-15 | 9545.25 |
|  3 | Jem 2 Sales 2    | From rathnapura store     | 2016-05-15 | 9545.25 |
|  4 | Jem 2 Sales 2    | From rathnapura store 234 | 2016-05-15 | 9545.25 |
+----+------------------+---------------------------+------------+---------+

Answer 1

Have a table of all the months and then left join<\/code> to your table:

SELECT MONTHNAME(m.month) AS mName, 
    MONTH(m.month) AS mOrder, 
    ifnull(sum(amount),0) AS total_num 
from months m
left join income i
on m.month = i.date

GROUP BY mOrder 
ORDER BY mOrder DESC

Answer 2

You should create a CALENDAR table, with the precision you need, in this case months.

+-----------+
| Month     |
+-----------+
| January   |   
| February  |      
.......

And Join on it

Answer 3

Maybe this it's not the best way to do it, but it will solve your problem. As a quick soution:

SELECT 'January' AS mName, 1 AS mOrder, COALESCE(SUM(amount),0) AS total_num 
FROM income i
WHERE month(i.date) = 1

UNION

SELECT 'February' AS mName, 2 AS mOrder, COALESCE(SUM(amount),0) AS total_num 
FROM income i
WHERE month(i.date) = 2

UNION

...and go on