qq_34097692的博客

SELECT DATE_FORMAT(dt.dtime, '%H:%i') tim, count(r.ID) AS numFROM ( SELECT @date := DATE_ADD(@date, INTERVAL + 1 HOUR) dtime FROM ( SELECT @date := DATE_ADD("2021-08-09 00:00:00", INTERVAL + 0 HOUR) FROM shop_visit_record .

在执行插入语句的时候出现 MySQL server has gone away错误 ，导致插入失败。解决方案：1.临时（重启服务后失效） 设置： set global max_allowed_packet=268435456;查看：show global variables like 'max_allowed_packet';2.一劳永逸修改mysql配置文件my.ini或...

 SQL语句：（传入用户当前距离：蓝色为纬度，红色为经度）SELECT *,SQRT(    POW(111.2 * (lat - 40.0844020000), 2) +    POW(111.2 * (116.3483150000 - lng) * COS(lat / 57.3), 2)) AS distanceFROM map HAVING distance < 2...