//定义数据模型类publicclassBase_UserTestDTO:Base_User{publicstring DepartmentName {get;set;}}//即BaseBusiness中的Servicevar db = DbFactory.GetRepository();
Expression<Func<Base_User, Base_Department, Base_UserTestDTO>>select=(a, b)=>newBase_UserTestDTO{
DepartmentName = b.Name
};select=select.BuildExtendSelectExpre();var q =from a in db.GetIQueryable<Base_User>().AsExpandable()join b in db.GetIQueryable<Base_Department>() on a.DepartmentId equals b.Idinto ab
from b in ab.DefaultIfEmpty()select @select.Invoke(a, b);//筛选varwhere= LinqHelper.True<Base_UserTestDTO>();where=where.And(x => x.UserName =="Admin");//获取筛选数据var list = q.Where(where).ToList();