mysql中将null值转换为0的语句

答案：
复制代码 代码如下:

SELECT 
IF(AVG(cai.conversionsRate) IS NULL,0,AVG(cai.conversionsRate)) 
AS conversionsRate 
FROM campaign_info cai 
WHERE insertTime BETWEEN '2011-02-01' AND '2011-02-04' AND googleCampaignId=23331401

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