避免MySql中的NULL引用结果

Question

我正在运行此查询。工作正常但是如果找到NULL结果，那么它会在我的应用程序中创建异常错误。如何避免NULL参考

SELECT SUM(pointsEarned) as earned, SUM(pointsRedeemed) as redeemed 
FROM `salesData` 
WHERE dealerID = @dealerID and status = 'active'

Answer 1

在COALESCE周围使用SUM。

SELECT COALESCE(SUM(pointsEarned),0) earned, COALESCE(SUM(pointsRedeemed),0) redeemed 
FROM salesData 
WHERE dealerID = @dealerID
AND status = 'active'