一.问题 groupBY分组后取最新一条记录的SQL的解决方案. 二.解决方案 select Message,EventTime from PT_ChildSysAlarms as a where EventTime = (select max(b.EventTime) from PT_ChildSysAlarms as b where a.PtName = b.PtName ) group by Message,EventTime order by EventTime desc
: failed to push some refs to 'git@github.com:AlanKnightly/reactC.git'hint: Updates were rejected because the tip of your current branch is behindhint: its remote counterpart. Integrate the remote changes (e.g.hint: 'git pull ...') before pushing aga
当使用GROUP BY 分组,默认返回的数据是组中最小的记录即id最小的数据, 当开发中经常会需要分组后将最新的数据放在前面, 为了实现需求,使用了嵌套查询,分别使用order by来排序 SELECT id, from_id, to_id, conversation_id, created_date, has_read, content FROM ( SELECT * FROM message WHERE from_id = 6 OR to_id = 6 ORDER BY created_da
有这样的一个需求:提交表单,如果用户没有登录,就跳转到登录页,登录后,跳转到原先表单提交这个页面,而且需要保持提交表单界面的数据. 提交表单的页面是一个强类型视图页,如果不考虑需要保持提交表单界面的数据,可以先设计这样的一个Model: public class Student { public string Name{get;set;} public string ReturnUrl{get;set;} } 在提交表单的视图页,大致这么写: @using (Html.BeginForm("In