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

本文详细介绍了如何使用SQL进行复杂的数据查询,包括通过LEFT JOIN实现数据对比,以及如何利用视图提高查询效率。文章提供了具体的SQL代码示例,展示了如何从订单信息中筛选已支付记录,并按用户ID和月份分组,最后通过日期比较实现数据连续性检查。
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