1、時間的比較
DATE_FORMAT(mc.create_time,'%Y-%m-%d %H:%i') > DATE_FORMAT(#{voCreateDate},'%Y-%m-%d %H:%i' )
2、IFNULL 如果爲空就返回
IFNULL(SUM(mc.gain_medicine_num),0)
3、字符拼接
CONCAT(FORMAT(( (t.totalByMonth) / (t.totalBuyPeople) * 100),2),'%') AS mouthDuty