MySQL求每个用户当月是否消费过

SELECT userId,DATE_FORMAT(paidTime,"%Y%m-01")
from learn.order_info_utf
GROUP BY userId,DATE_FORMAT(paidTime,"%Y%m-01")

• 使用left join

SELECT t1.m,count(t1.m),count(t2.m) FROM (
	SELECT userId,DATE_FORMAT(paidTime,"%Y-%m-01") as m
	from learn.order_info_utf
	WHERE Ispaid = "已支付"
	GROUP BY userId,DATE_FORMAT(paidTime,"%Y-%m-01")) t1
left JOIN (
	SELECT userId,DATE_FORMAT(paidTime,"%Y-%m-01") as m
	from learn.order_info_utf
	WHERE Ispaid = "已支付"
	GROUP BY userId,DATE_FORMAT(paidTime,"%Y-%m-01")) t2
ON  t1.userId = t2.userId and t1.m = DATE_SUB(t2.m,INTERVAL -1 MONTH)
GROUP BY t1.m

*注意【%Y-%m-01】之间的【-】

• 最好创建view，更有效率

create algorithm = undefined view tmp
as  
SELECT userId,DATE_FORMAT(paidTime,"%Y%m-01")
from learn.order_info_utf
GROUP BY userId,DATE_FORMAT(paidTime,"%Y%m-01")

SELECT t1.m,count(t1.m),count(t2.m) FROM tmp as t1
left JOIN tmp as  t2
ON  t1.userId = t2.userId and t1.m = DATE_SUB(t2.m,INTERVAL -1 MONTH)
GROUP BY t1.m