在sql中,如果有group by,那么select的字段只能包含分组内容,或者count.sum.avg这些统计字段. 但在linq里面,是:group 你想要什么字段 by 分组字段 比如: var q = from p in db.Products group p by p.CategoryID into g select g; 实际应用中,多表多字段参与分组比较常见: from a in TableA join b in TableB on a.Id equals b.aId || b.

Linq to sql 使用group by 统计多个字段,然后返回多个字段的值,话不多说,直接上例子: where u.fy_no == fy_no orderby u.we_no group u by new { weno = u.we_no, wename = u.we_name } into g select new { g.Key.weno, g.Key.wename }; 结果就是根据we_no和we_name的统计结果,返回这两个字段的数据.

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.Products group p by p.CategoryID into g select g; 语句描述:使用Group By按CategoryID划分产品. 说明:from p in db.Products 表示从表中将产品对象取出来.group p by p.CategoryID i

http://wenku.baidu.com/link?url=2RsCun4Mum1SLbh-LHYZpTmGFMiEukrWAoJGKGpkiHKHeafJcx2y-HVttNMb1BqJpNdwaOpCflaajFY6k36IoCH_D82bk2ccu468uzDRXvG 基于LINQ+to+Entity数据访问技术的应用研究 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:

本文转自:http://www.cnblogs.com/jack-liang/archive/2011/03/22/1991554.html 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.Products group p by p.CategoryID into g select g; 语句描述:使用Group By按CategoryI

linq 是我们在查询中经常回用到的一种形式,比如我们创建一个类,然后List<添加> 并绑定到表格中 public class Modeltest { string id; public string Id { get { return id; } set { id = value; } } string pwd; public string Pwd { get { return pwd; } set { pwd = value; } } string name; public string

Ø  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 UserN

LINQ: var temp = from p in db.jj_Credentials group p by p.ProfessionID into g select new { g.Key, MaxPrice = g.Max(p => p.CredentialsRankID) }; EF: var temp1 = db.jj_Credentials.GroupBy(m => m.ProfessionID).Select(m => m.Max(o => o.Credentials

本文转载自:http://www.cnblogs.com/sydeveloper/archive/2013/03/29/2988669.html 1.用两层循环计算,前提条件是数据已经按分组的列排好序的. DataTable dt = new DataTable(); dt.Columns.AddRange(new DataColumn[] { new DataColumn("name", typeof(string)), new DataColumn("sex",

在linq中排序方法有: OrderBy()  --对某列升序排序 ThenBy()    --某列升序后对另一列后续升序排序 OrderByDescending() --对某列降序排序 ThenByDescending() --某列降序后对另一列后续降序排序 举例: 1.现在对集合AllSubjectList按字段column1升序排序后,再按照column2升序排序 <1. var lvThirdSubList =AllSubjectList.OrderBy(m => m.column1)

var list = from item in (from s in _sysBll.GetList(s => s.ParamID == "TraSchType" && s.ParamCode != null) join t in data on s.ParamCode equals t.TraSchType into tmp from f in tmp.DefaultIfEmpty() select new { value = tmp.Count(), name

].AsEnumerable() group c by c.Field<int>("Name") into s select new { ID = s.Select(m => m.Field<int>("ID").ToString()), Name = s.Select(m => m.Field<string>("Name").ToString()), Math = s.Sum(p => p.

如tb_flag 数据结构如下:flag int null 不能使用:flag==null 生成的SQL语句为 where flag=null   建议使用:可空类型 用Nullable<T>.Equals(字段,值)var query=from f in db.tb_flagwhere Nullable<int>.Equals(f.flag,null) select f;  生成的SQL语句为 where flag is null

1.更新单个字段 /// <summary> /// 更新字段 /// </summary> /// <typeparam name="T"></typeparam> /// <param name="conditions">where 筛选对象</param> /// <param name="updateLamda">更新字段</param> //

本文转自:https://stackoverflow.com/questions/530925/linq-using-inner-join-group-and-sum SELECT T1.Column1, T1.Column2, SUM(T3.Column1) AS Amount FROM T1 INNER JOIN T2 ON T1.T1ID = T2.T1ID INNER JOIN T3 ON T2.T3ID = T3.T3ID GROUP BY T1.Column1, T1.Column2

private void cmbStore_SelectedIndexChanged(object sender, EventArgs e) { DataTable vDt = ParamClass.ChargDt; var q = from b in vDt.AsEnumerable() group b by new { storeid = b["STOREID"], charg = b["charg"] } into g select new { g.Key.s

(from s in dc.StockInItem   //所要查询单表 join si in dc.StockIn           //联合的表 on s.StockInID equals si.StockInID     //两个表联合的相同条件 where (s.ColorsID == int.Parse(colorID) && s.SizesID == int.Parse(sizeID) && s.ProductID == int.Parse(ProtectID

from VS in m2db.Inf_VehicleSale join RS1 in m2db.His_RecSale on new { VS.vehicleCode, auctionCode=VS.AuctionCode } equals new { RS1.vehicleCode, RS1.auctionCode }

1.ydc.GameScore.OrderByDescending(o => o.Score).GroupBy(ic => ic.UserPhone).Select(g => g.First());

xxxxxxxx.Sum(f => f.jifen).GetValueOrDefault(0)

var query = from main in _userDeviceChannelRole.Table join deviceChannelInfo in _deviceChannelRepository.Table on new { main.DeviceId, main.ChannelNumber } equals new { deviceChannelInfo.DeviceId, deviceChannelInfo.ChannelNumber } select new { };