Select

===============Join=============

public List<CustomersInfoModel> GetCmpInfo()
        {

            try
            {
                ComDataContext _context = new ComDataContext(ComDataContext.ConneStr);
                var t = (from a in _context.UserRoleRelationModel
                         join b in _context.UserInfoModel on a.Usr_Id equals b.Usr_Id
                         join c in _context.CustomersInfoModel on b.Cmp_No equals c.Cmp_No
                         where a.Role_Id == Utility.ManagementContext.C_LOGISTICSBUSINESS
                         select c).ToList();
                return t;
            }
            catch (Exception ex)
            {
               

            }
        }

===============分页查询,返回IQueryable,Where==============

 public static IQueryable Search(TaskInfoModel _TaskInfoModel, int pageIndex, int pageSize, out int totalCount)
        {
            ComDataContext context = new ComDataContext(ComDataContext.ConneStr);
            totalCount = 0;

            var objWhere = LinqWhere.True<TaskInfoModel>();

            if (!string.IsNullOrEmpty(_TaskInfoModel.Task_Init ))
            {
                objWhere = objWhere.And(p => p.Task_Init.Contains(_TaskInfoModel.Task_Init)); // 模糊查询
            }
            pageIndex++;
            if (pageIndex < 0) pageIndex = 1;

                     var t = (from objTableA in context.TaskInfoModel.Where(objWhere)
                       select new
                     {
                         objTableA.Task_No ,
                                              }).OrderByDescending(p => p. First_Dt);

            totalCount = t.Count();

            return t.Skip((pageIndex - 1) * pageSize).Take(pageSize);
        }

============直接返回List=============

private List<ViewModel> GetView()
        {
             ComDataContext _context = new ComDataContext(ComDataContext.ConneStr);
             try
             {
                 var t = (from a in _context.ViewModel select a).ToList();
                 return t;
             }
             catch (Exception e)
             {
              }
        }

===========Single查询============

public string No(string Id)
        {
            ComDataContext context = new ComDataContext(ComDataContext.ConneStr);
               Model model = context.Model.SingleOrDefault(p => p.Usr_Id == Id);

  }