mysql if,date 运用例子(统计每人每月浏览日报次数)

统计每个人每个月日报次数

SELECT c.*,if(mm.month,mm.month,0) month,if(mm.sum,mm.sum,0) sum
FROM admin c
LEFT JOIN (
　　SELECT a.id,a.numb,a.name, DATE_FORMAT(add_time, '%Y-%m') MONTH, COUNT(b.user_id) SUM
　　FROM admin a
　　LEFT JOIN daily b ON a.id=b.user_id
　　WHERE YEAR(b.add_time) = 2016 AND MONTH(add_time)=11
　　GROUP BY a.id) mm
ON c.id = mm.id