问题描述
我希望根据PaymentStatus值从两个不同的列获得支付状态的总和-但此查询返回NULL作为总和。为什么它不工作？select payment_status,
CASE
WHEN 'PAID' THEN sum(paid_amount)
when 'Not Paid' then sum(total_amount_due )
END
from monthly_fee
group by payment_status;
推荐答案
您可以尝试以下查询：
select sum(if(payment_status = 'PAID', paid_amount, 0)
+ if(payment_status = 'Not Paid', total_amount_due, 0))
from monthly_fee
group by payment_status;