var result = from temp2 in ( from u in users.Tables[0].AsEnumerable() join s in hpcSummary.Tables[0].AsEnumerable() on u.Field<String>("DomainUser") equals s.Field<String>("CountObj") select new { SolverName ...
使用Linq group by 查询 一般我们都会这样写Linq：var result = (from si in model.table group si by si.NumCores into grp orderby grp.Key select new CoreCount { Cores = grp.Key, Count = grp.Count() }).ToList();正确的答案（MySql）： var result = (from si in model.table group si by si.NumCores into grp orderby grp.Key select new CoreCount { Cores = grp.FirstOrDefault().NumCores, Count = grp.Count() }).To...
,MAX(photourl) from (select b.PhotoAlbumID,b.PhotoUrl,a.ID,a.PhotoAlbumName,a.Describe from PhotoAlbum as a inner join Photos as b on a.ID=b.PhotoAlbumID) as cgroup by PhotoAlbumName,Describe,PhotoAlbumID linq: var photolist2 = (from a in db.PhotoAlbum join b in db.Photos on a.ID equals b.PhotoAlbumID group new { a, b } by new { a.PhotoAlbu...
我们继续讲解LINQ to SQL语句，这篇我们来讨论Group By/Having操作符和Exists/In/Any/All/Contains操作符。 Group By/Having操作符 适用场景：分组数据，为我们查找数据缩小范围。 说明：分配并返回对传入参数进行分组操作后的可枚举对象。分组；延迟 1.简单形式： var q =from p in db.Productsgroup p by p.CategoryID into gselect g; 语句描述：使用Group By按CategoryID划分产品。 说明：from p in db.Products 表示从表中将产...
前言 本示例主要实现 LINQ 查询，先分组，再聚合，最后在排序。示例很简单，但是使用 LINQ 却生成了不同的 SQL 实现。 1) 采用手动编写 SQL 实现 SELECT ROW_NUMBER() OVER(ORDER BY T.RealTotal DESC) AS SN, * FROM ( SELECT (SELECT TradeName FROM UserInfo AS T2 WHERE T2.Id=T1.UserId) AS TradeName, (SELECT UserName FROM UserInfo AS T2 WHERE T2.Id=T1.UserId) AS UserName, SUM(T1.RealTotal) AS RealTotal...
}).ToList();正确的答案（MySql）： var result = (from si in model.table group si by si.NumCores into grp orderby grp.Key select new CoreCount { Cores = grp.FirstOrDefault().NumCores, Count = grp.Count() }).ToList();以上在MySQL亲测有效，SQL server没有测试。。。C# linq group by 异常 -----MySqlException: Unknown column GroupBy1.K1 in field list标签：lis 答案 cores orderby mod sele mode m...
我有以下型号：public class Course {public int Id { get; set; }public string Name { get; set; } }public class Course_TutionCenter {public int Id { get; set; }public int CourseId { get; set; }public int TutionCenterId { get; set; }[ForeignKey("CourseId")]public virtual Course Course { get; set; }[ForeignKey("TutionCenterId")]public virtual TutionCenter TutionCenter { get; set; } }public class Course...
我有一个调用MySQL过程的方法.以下是程序的一部分：SELECT AR.alert_id AS AlertId,AR.rule_id AS RuleId,AR.name AS RuleName,AR.rule_type AS RuleType, AR.description AS Description, (SELECT group_concat(occured_event_id separator ', ') FROM alert_rule_eventWHERE alert_rule_id = AR.id) AS OccuredEventIds, FROM alert_rule ARC#代码：alertRuleEntity.AlertId = Convert.ToInt32(dtAlertRuleEntityList.Rows[index...
考虑以下对象：public class Address { public string city; public string state; public string country; }如果我有一个地址列表,我将如何使用LINQ获取城市,州和国家匹配的计数列表. 所以我的结果看起来像这样： >“princeton”“nj”“usa”122>“奥斯汀”“tx”“美国”44>“la”“ca”“usa”1>“princton”“na”“uk”3> …. 谢谢！解决方法:比Marc的答案更进了一步(他在我发布之前编辑过！).大声笑var qry = from addr in ...
我必须在lambda表达式中转换我给定的linq查询.即var scholars = (from scholar in db.Scholarsjoin suspension in db.Suspensions on scholar.ID equals suspension.ScholarIDwhere suspension.StartDate >= startDate && suspension.EndDate <= endDategroup scholar by new { scholar.ID, scholar.FirstName, scholar.LastName }into gselect new{FullName = g.Key.FirstName +" " + g.Key.LastName,TotalSuspensionSum = g.Sum(...
这是数据结构,我从NHibernate Query回来了public Class PaperResult {public Guid SubjectId {get;set}public Guid StudentId {get;set}public string Name {get;set}public string Email {get;set}public int Marks {get;set}}我的疑问是var resultEntities = _repository.Query<PaperResult>().where(t => t.Id == testId) studentResults = resultEntities.GroupBy(x => x.StudentId)返回,IQueryable,现在我把它投射到课堂上p...
做了很多研究,但仍然有一个艰难的研究.考虑具有“CreatedOn”,“Amount”,“Type”的事务表的数据库.我需要能够进行实体查询以获得按不同日期粒度(月/日等)组合在一起的特定类型的事务. 想象一下一张桌子：2011/1/22 $300 Deposit 2011/2/18 $340 Deposit 2011/3/6 $200 Other 2011/3/6 $100 Deposit 2011/3/7 $50 Deposit我可以有一个查询,它将按月分组所有存款,以便它可以产生：2011-1 $300 1deposit 20...
我将WPF ListBox绑定到分组的ICollectionView. ListBox正确显示组标题,但我想为此添加其他行为. 我希望组标题保持在顶部,直到下一个组标题导致它滑出视图.这类似于IPhone联系人列表的工作方式,其中标题“A”,“B”,“C”一直贴在顶部,直到下一个字母类别替换它.我认为这将是一个受欢迎的功能,但我无法在网上找到这个例子.解决方法:很老的问题,但这里是我将如何处理您的要求(在WPF中显示ListBox / List视图的“Sticky Group Headers...
假设我们有一个允许用户下载内容的项目.在主页面上,我想显示下载次数最多的下载文件！所有使用EF. 我怎样才能做到这一点 ！！我用Group By尝试了很多东西(当你在对象中获得大量信息时,这是一场噩梦).我仍然不知道如何做到这一点……var query = from details in m_context.TransactionDetailswhere details.Chanson != nullgroup details by details.Items into AnItemorderby AnItem.Count()select new Item() {IdItem = Chansons...
大家好我对Linq有疑问. 我将结果分组到客户邮政编码上.对于每个邮政编码,我想查看预订量和订购的设备数量. 到目前为止我的代码看起来像这样：var statistics = from b in db.Bookingsfrom c in db.Customerswhere b.customerID == c.idgroup c by c.zipcode into statselect new { Zipcode = stat.Key, NumberOfBookings = stat.Count() };此代码组生成zipcodes,并为我提供每个邮政编码中的预订量.如何获得设备数量？解决方法:您可...