为什么mysql总和不工作在MySQL视图表中？

Question

我使用下面的查询，以从MySQL获得观看表

Select regd, date, subject, (t_scored+w_scored+f_scored+cce_scored) as Total 
from 
exam_view 
where regd='3' 
group by subject 

总成绩列总我只得到NULL那里有各入一球域的域值。请任何人都可以帮我吗？

Answer 1

使用内嵌查询以获得独立资金，而外部查询加起来的总和

SELECT regd, date, subject, SUM(t_scored+w_scored+f_scored+cce_scored) AS total 
FROM 
(
SELECT regd, date, subject, SUM(t_scored) as t_scored, SUM(w_scored) as w_scored, SUM(f_scored) AS f_scored, SUM(cce_scored) AS cce_scored 
FROM 
exam_view 
WHERE regd='3' 
) AS temp 
GROUP BY subject