linq - 如何使用 Linq C# 获取层次结构

Question

我遇到了 linq c# 的问题，我的数据库中有三个表首先是 tbl_ActivitiesMaster (this contain Parent Child Data)

CREATE TABLE  
tbl_ActivityMaster
(intActivityId int IDENTITY(1,1) NOT NULL,  
strActivityDesc varchar(max) NULL,  
intActivityUOMId int,
dtDatetime datetime,
IsParentActivity int,
IsAlerternateActivity int NULL,
intParentToId int NULL,
intTaskId int NULL,
intAlternateId int NULL,
CONSTRAINT PK_tbl_ActivityMaster PRIMARY KEY CLUSTERED  (   
[intActivityId] ASC )
WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS 
= ON, ALLOW_PAGE_LOCKS  = ON) 
ON [PRIMARY] ) ON [PRIMARY]

其次是tbl_TendersTaskActivities

CREATE TABLE tbl_TendersTaskActivities(
    intID [int] IDENTITY(1,1) NOT NULL,
    intTaskId [int] NULL,
    intTenderId [int] NULL,
    intProjectWorkGroupId [int] NULL,
    intActivityId [int] NULL,
    ftActivityQty [float] NULL,
    ftActivityRate [float] NULL,
    intUomId int NULL,
    dtTaskStartDate [datetime] NULL,
    dtTaskCompletionDate [datetime] NULL,
    intFlag [int] NULL,
    IsCanceled [bit] NULL,
 CONSTRAINT [PK_tbl_TendersTask] PRIMARY KEY CLUSTERED 
(
    [intID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

我想要来自表 tbl_TendersTaskActivities 的数据，其中活动的父级作为层次结构输出请有人可以解决这个问题提前谢谢。

Answer 1

from m in DataContext.tbl_ActivityMaster
             join d in DataContext.tbl_TendersTaskActivities on m.intActivityId equals d.intActivityId    into temp
             from t in temp.DefaultIfEmpty()
             group SysDocument by m

Answer 2

在 LinqToSql 中，您将使用DataLoadOptions拉入相关记录：

DataLoadOptions myOptions = new DataLoadOptions();
myOptions.LoadWith<ActivityMaster>(x => x.TendersTaskActivities);

using (CustomDataContext myDC = new CustomDataContext(connStr))
{
  myDC.LoadOptions = myOptions;

  List<ActivityMaster> masters = myDC.ActivityMasters
    .Where(filter)
    .ToList();  //TendersTaskActivities also loaded.
  return masters; 
}