GROUP结果值，如果为null

Question

我无法执行此查询：

TABLE：

------------
NOTES  | TOTAL
------------
NULL    |  23
NULL    |  12
pay1    | -13
pay2    | -23
-------------

结果：

------------
NOTES   | TOTAL
------------
SELL    |  35
pay1    | -13
pay2    | -23
-------------

我需要对所有NULL字段和名称为“SELL”的组进行求和。

Answer 1

select IFNULL(NOTES,'SELL') n,SUM(TOTAL) FROM records GROUP BY n;

Answer 2

使用IF条件语句检查名称列为NULL值，并替换为＆＃34; SELL＆＃34; 文本。

select IF(name is  NULL, "SELL", name) as name, sum(total) as total from content group by name;

Answer 3

SELECT 
IFNULL(NOTES,'SELL')as NOTES,
SUM(TOTAL)  as TOTAL
FROM records 
GROUP BY notes
ORDER BY IFNULL(NOTES,'a')