数据库转化null值_MySQL

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

        /*MS-SqlServer去除NULL值*/<br>        select ISNULL(avg(cai.conversionsRate),0)<br>        AS conversionsRate<br>        FROM campaign_info cai<br>        WHERE insertTime BETWEEN '2010-02-11' AND '2011-01-23' AND googleCampaignId=42722951