如果有0個實體，則用空值來表示月份的Mysql組

Question

真的很簡單（在這裏找不到示例）。基本上我想添加缺失月份的空值。

目前我有

|month| total | 
---------------- 
    2 | 2454.34 
    3 | 1254.34 

在哪裏，因爲我想

|month| total | 
---------------- 
    1 | 0 
    2 | 2454.34 
    3 | 1254.34 
    4 | 0 
    5 | 0 
    6 | 0 

等。

我的查詢到目前爲止

SELECT MONTH(bookings.booking) as month, SUM(bookings.tendered) as total 
FROM bookings 
INNER JOIN salons ON salons.id = bookings.salon_id 
WHERE bookings.paid = 1 
AND YEAR(bookings.booking) = 2017 
GROUP BY MONTH(bookings.booking) 
ORDER BY MONTH(bookings.booking); 

我曾嘗試以下，但似乎並沒有工作，我希望它的方式？從例如

SUM(IF(MONTH(bookings.booking) = 'Jan', bookings.tendered, 0)) AS 'Jan', 
     SUM(IF(MONTH(bookings.booking) = 'Feb', bookings.tendered, 0)) AS 'Feb', 
     SUM(IF(MONTH(bookings.booking) = 'Mar', bookings.tendered, 0)) AS 'Mar', 
     SUM(IF(MONTH(bookings.booking) = 'Apr', bookings.tendered, 0)) AS 'Apr', 
     SUM(IF(MONTH(bookings.booking) = 'May', bookings.tendered, 0)) AS 'May', 
     SUM(IF(MONTH(bookings.booking) = 'Jun', bookings.tendered, 0)) AS 'Jun', 
     SUM(IF(MONTH(bookings.booking) = 'Jul', bookings.tendered, 0)) AS 'Jul', 
     SUM(IF(MONTH(bookings.booking) = 'Aug', bookings.tendered, 0)) AS 'Aug', 
     SUM(IF(MONTH(bookings.booking) = 'Sep', bookings.tendered, 0)) AS 'Sep', 
     SUM(IF(MONTH(bookings.booking) = 'Oct', bookings.tendered, 0)) AS 'Oct', 
     SUM(IF(MONTH(bookings.booking) = 'Nov', bookings.tendered, 0)) AS 'Nov', 
     SUM(IF(MONTH(bookings.booking) = 'Dec', bookings.tendered, 0)) AS 'Dec', 
     SUM(tendered) AS total 

修訂

select `a`.`month` as `month_int`, IFNULL(SUM(bookings.tendered), 0) as total from `bookings` right join (
SELECT 1 as month 
UNION SELECT 2 as month 
UNION SELECT 3 as month 
UNION SELECT 4 as month 
UNION SELECT 5 as month 
UNION SELECT 6 as month 
UNION SELECT 7 as month 
UNION SELECT 8 as month 
UNION SELECT 9 as month 
UNION SELECT 10 as month 
UNION SELECT 11 as month 
UNION SELECT 12 as month\n 
) a on `a`.`month` = MONTH(bookings.booking) where `bookings`.`paid` = ? and date(`bookings`.`booking`) > ? and `salon_id` in (?, ?, ?) group by `a`.`month` 

Answer 1

此代碼將工作

SELECT m.MONTH as month, 
CASE 
    WHEN SUM(b.total) > 0 THEN SUM(b.total) 
    ELSE 0 END as total 
FROM 
(
SELECT '01' AS 
MONTH 
UNION SELECT '02' AS 
MONTH 
UNION SELECT '03' AS 
MONTH 
UNION SELECT '04' AS 
MONTH 
UNION SELECT '05' AS 
MONTH 
UNION SELECT '06' AS 
MONTH 
UNION SELECT '07' AS 
MONTH 
UNION SELECT '08' AS 
MONTH 
UNION SELECT '09' AS 
MONTH 
UNION SELECT '10' AS 
MONTH 
UNION SELECT '11' AS 
MONTH 
UNION SELECT '12' AS 
MONTH 
) AS m 
LEFT JOIN 
(SELECT MONTH(b.bookings) AS 'month', SUM(b.tendered) AS 'total' 
FROM bookings AS b 
INNER JOIN salons AS s 
ON s.id = b.salon_id 
WHERE b.paid = 1 
AND YEAR(b.booking) = 2017) AS n 
ON 
m.MONTH = n.month 
GROUP BY 1 
ORDER BY 1; 

Answer 2

上述對不起不同的格式，你可以在網上看到這個例子：http://sqlfiddle.com/#!9/8bbf0/1

SELECT 
    idMonth, 
    MONTHNAME(STR_TO_DATE(idMonth, '%m')) as m, 
    IFNULL(sum(Bookings.price), 0) as total 
FROM Bookings 
RIGHT JOIN (
    SELECT 1 as idMonth 
    UNION SELECT 2 as idMonth 
    UNION SELECT 3 as idMonth 
    UNION SELECT 4 as idMonth 
    UNION SELECT 5 as idMonth 
    UNION SELECT 6 as idMonth 
    UNION SELECT 7 as idMonth 
    UNION SELECT 8 as idMonth 
    UNION SELECT 9 as idMonth 
    UNION SELECT 10 as idMonth 
    UNION SELECT 11 as idMonth 
    UNION SELECT 12 as idMonth 
) as Month 
ON Month.idMonth = month(`date`) 
GROUP BY Month.idMonth