如何从linq中的select new子句中选择记录

Question

I have the following code I am having 3 tables as Department, DepartmentTask and DepartmentPosition. Here are the tables :

public partial class Department()
{
   public int DepartmentId { get; set; }
   public string DepartmentName { get; set; }
   public Nullable<int> ParentDepartmentId { get; set; }    
}
public partial class DepartmentPosition
{
    public int PositionId { get; set; }
    public int DepartmentId { get; set; }
    public string PositiontName { get; set; }        
}
public partial class DepartmentTask
{
    public int TaskId { get; set; }
    public int DepartmentId { get; set; }
    public string TaskName { get; set; }       
}

So any department can be a parent to another department, Task and Position. So here I want to select all the records from the tables which are children of a particular Department based on DepartmentId.

var z = from n in dbbs.Department
        select new
        {
            deptcount = dbbs.Department.Count(p => p.ParentDepartmentId == id),
            poscount = dbbs.DepartmentPosition.Count(x => x.DepartmentId == id),
            taskcount = dbbs.DepartmentTask.Count(t => t.DepartmentId == id)
        };
if(z.Count()>0)
{ 
//do something
}
else
{

}

and now if there are no record within tables still it is coming within if block. I want to know how to restrict if there are no records as per the query.

Answer 1

I'm not sure what you are trying to achieve with the select statement. Can you not use:

var deptcount = dbbs.Department.Count(p => p.ParentDepartmentId == id);
var poscount = dbbs.DepartmentPosition.Count(x => x.DepartmentId == id);
var taskcount = dbbs.DepartmentPosition.Count(t => t.DepartmentId == id);

if(deptcount > 0) 
{
 //do something
}

if you are trying to do a grouping based on the departments please explain and I'll update my answer.

Answer 2

var count= from s in ObjectContext.tb1
                              join c in ObjectContext.tb2 on s.ParentCategoryID equals c.PersonCategoryID
                              join p in ObjectContext.tb3 on c.BusinessEntityID equals p.BusinessEntityID
                              select new count()
                              {
                                 tbl1count =c.count()
                                 tbl2count =p.count()
                                 tbl3count =p.count()
                              };

then

if(count.tbl1count.any()){
//do whatever you need}