EF 多表查询的方法

EF实体类 entity = new EF实体类();

var query = (from u in entityt.用户表 join b in entity.权限表 on u.用户权限Id equls b.Id where u.用户Id == 1 select u).FirstOrDefault();

两个表的linq 
        private DataClasses1DataContext dc;

         dc = new DataClasses1DataContext();

 var heji = (from da in dc.q1
                              join du in dc.q2
                              on da.danhao equals du.danhao
                              where da.hetong == "XXXX"

                              select new { du.color1,  da.danhao, da.riqi, du.zhongliang, du.beizhu }).Distinct();

关于linq的多表联查效果的实现：

后台多表查询  内连接：

SELECT
[Extent2].[partID] AS [partID],
[Extent1].[userName] AS [userName],
[Extent3].[partName] AS [partName]
FROM [dbo].[User] AS [Extent1]
INNER JOIN [dbo].[User_partB] AS [Extent2] ON [Extent1].[userGUID] = [Extent2].[userGUID]
INNER JOIN [dbo].[partB] AS [Extent3] ON [Extent2].[partID] = [Extent3].[partID]

var userListTest = (from u in db.Users
                                join p in db.User_partB on u.userGUID
              equals p.userGUID
                                join d in db.partBs on p.partID equals d.partID
                                select new { name = u.userName, departName = d.partName });
            List oneList = new List();
            foreach (var one in userListTest.ToList())
            {
                dynamic dyObject = new ExpandoObject();
                dyObject.userName = one.name;
                dyObject.departName = one.departName;
                oneList.Add(dyObject);
            }
            ViewBag.dyObject = oneList;
            return View();

前台数据数据表示的方法：
 

<table>
    <tr><td>用户登录名td><td>姓名td><td>状态td><td>角色td><td>操作td>tr>
    @{foreach (var one in ViewBag.dyObject)
    {
        <tr>
            @*<td>@one.userLoginNametd>*@
            <td>@one.userNametd>
            @*<td>@one.active==1?"启用":"禁用"td>*@
            <td>@one.departNametd>
            <td>td>
        tr>
    }
    }
table>

linq  多表联查 外链接：

SELECT
1 AS [C1],
[Extent1].[userName] AS [userName],
[Extent3].[partName] AS [partName]
FROM [dbo].[User] AS [Extent1]
LEFT OUTER JOIN [dbo].[User_partB] AS [Extent2] ON [Extent1].[userGUID] = [Extent2].[userGUID]
LEFT OUTER JOIN [dbo].[partB] AS [Extent3] ON [Extent2].[partID] = [Extent3].[partID]

var userListTest = (from u in db.Users
                                join p in db.User_partB on u.userGUID
              equals p.userGUID into temp
                                from t in temp.DefaultIfEmpty()
                                join d in db.partBs on t.partID equals d.partID
                                into tempone
                                from user in tempone.DefaultIfEmpty()
                                select new { name = u.userName, departName = user.partName });
            List oneList = new List();
            foreach (var one in userListTest.ToList())
            {
                dynamic dyObject = new ExpandoObject();
                dyObject.userName = one.name;
                dyObject.departName = one.departName;
                oneList.Add(dyObject);
            }
            ViewBag.dyObject = oneList;
            return View();

前台数据展示效果同上

上述过程中，遇到  延迟加载后的动态数据，TOList()之后，传递到前台后，在foreach循环时，无法通过对象.属性的形式，读取出来，报“OBJECT未定义该属性”，经过查找原因发现，该动态数据为internal类型，只能同一程序集内访问，找了若干方法，不太适用，当然，如果大家有好的建议，可以一起交流讨论，究于当前场景，我选择了ExpandoObject，来动态处理，linq的查询结果。