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Get parent department node in Entity Framework

I have a SQL table like this:
DepartmentID is parent of department. I've build a tree by this table(in ASP.net (C#) project):
Records in tree above is:
I need to get parents in this tree.
I can do it in SQL Server like this(for Example id=2, id is input argument):
with cte1
as
(
select id,name,DepartmentID, 0 AS level
from Department
where id =2
union all
select Department.ID,Department.name,Department.DepartmentID, level+1
from Department
inner join cte1 on Department.ID=cte1.DepartmentID
)
select * from cte1
Output(id=2 (A))
Output(id=4 (A1))
I know EF does not support cte, but I need to get this result in EF.
It would be very helpful if someone could explain solution for this problem.

These posts are similar to your question.please see these:
writing-recursive-cte-using-entity-framework-fluent-syntax-or-inline-syntax
converting-sql-statement-that-contains-with-cte-to-linq
I think there is no way to write a single LINQ to SQL query that could get all However, LINQ supports a method to execute a query (strangly enough called DataContext.ExecuteQuery). Looks like you can use that to call a arbitrary piece of SQL and map it back to LINQ.
See this post:
common-table-expression-in-entityframework

The easiest way I can think of is to map the relationship in EF and then retrieve all departments and then get the root parent from that list. All of them should be loaded in memory and EF will take care of the tree structure with the mapping. Alternatively you can enable lazy loading and just get the parent but then with each child or childset a query will be executed by EF during retrieval.
Model
public class Department
{
public int Id { get; set; }
public string Name { get; set; }
public int? DepartmentId { get; set; }
public Department ParentDepartment { get; set; }
public virtual ICollection<Department> ChildDepartments { get; set; }
}
Mapping (using fluent)
public DbSet<Department> Departments { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
// other mapping code
modelBuilder.Entity<Department>()
.HasOptional(x => x.ParentDepartment)
.WithMany(x => x.ChildDepartments)
.HasForeignKey(x => x.DepartmentId);
// other mapping code
}
Eager retrieval of root parent
using (var context = new YourDbContext())
{
var allDepartments = context.Departments.ToList(); // eagerly return everything
var rootDepartment = allDepartments.Single(x => x.DepartmentId == null);
}
Retrieval of only root parent and then use lazy loading, note that the DbContext needs to be available for Lazy Loading to work and it must also be enabled on the DbContext
using (var context = new YourDbContext())
{
var rootDepartment = context.Departments.Single(x => x.DepartmentId == null);
// do other stuff, as soon as context is disposed you cant lazy load anymore
}

Try one of these,
1-
int _ID = 2; // ID criteria
List<object> result = new List<object>(); // we will use this to split parent at child, it is object type because we need Level
var departments = entites.Departments.Where(x => x.ID == _ID).SelectMany(t => entites.Departments.Where(f => f.ID == t.DepartmentID),
(child, parent) => new { departmentID = child.DepartmentID, Name = child.Name, ID = child.ID, level = 0,
Parent = new { DepartmentID = parent.DepartmentID, Name = parent.Name, ID = parent.ID, level = 1 }});
// first we check our ID (we take A from where criteria), then with selectmany T represents the Department A, we need
// department A's departmentID to find its parent, so another where criteria that checks ID == DepartmentID, so we got T and the new list
// basically child from first where parent from second where, and object created.
// for showing the results
foreach (var item in departments)
{
result.Add(new { DepartmentID = item.departmentID,ID = item.ID, level= item.level,Name = item.Name}); // child added to list
result.Add(new { DepartmentID = item.Parent.DepartmentID, ID = item.Parent.ID, level = item.Parent.level, Name = item.Parent.Name }); // parent added to list
}
Result;
2-
List<object> childParent = new List<object>();
// basically get the child first
Departments child1 = entites.Departments.Where(x => x.ID == _ID).FirstOrDefault();
// find parent with child object
Departments parent1 = entites.Departments.Where(x => x.ID == child1.DepartmentID).FirstOrDefault();
// create child object with level
childParent.Add(new { child1.DepartmentID, child1.ID,child1.Name , level = 0});
// create parent object with level
childParent.Add(new { parent1.DepartmentID,parent1.ID,parent1.Name, level = 1 });
Result (not the same image, check column Header Text);
Edit 1:
3-
Another way, by giving ID as input and assuming that ID column is unique, so there will be always 2 values at the array and by returning list, the index of items actually represent their levels. (won't add results because they are same :)).Btw you can also use Union instead of Concat.
var ress = list.Where(x=> x.ID ==2)
.SelectMany(x=> list.Where(c=> c.ID == x.ID).Concat(list.Where(s => s.ID == x.DepartmentID))).ToList();
DataTable dt = new DataTable();
dt.Columns.Add("DepartmentID");
dt.Columns.Add("ID");
dt.Columns.Add("Name");
dt.Columns.Add("Level");
for (int i = 0; i < ress.Count(); i++)
{
dt.Rows.Add(ress[i].DepartmentID, ress[i].ID, ress[i].Name, i);
}
dataGridView1.DataSource = dt;
Edit 2
There is not cte in linq, basically using view,sp is the first choise but here is a solution, it might be a little push. Anyway it gives the result.
List<Departments> childParent = new List<Departments>();
// or basically get the child first
Departments child1 = entites.Departments.Where(x => x.ID == 7).FirstOrDefault();
// find parent with child object
Departments parent1 = entites.Departments.Where(x => x.ID == child1.DepartmentID).FirstOrDefault();
// create child object with level
Departments dep = new Departments(); // I add to department class a string level field
dep.DepartmentID = child1.DepartmentID;
dep.ID = child1.ID;
dep.Name = child1.Name;
dep.level = 0; // first item
childParent.Add(dep);
// create parent object with level
dep = new Departments();
dep.DepartmentID = parent1.DepartmentID;
dep.ID = parent1.ID;
dep.Name = parent1.Name;
dep.level = 1; // parent one
childParent.Add(dep);
while (childParent.Select(t => t.DepartmentID).Last() != null) // after added to list now we always check the last one if it's departmentID is null, if null we need to stop searching list for another parent
{
int? lastDepID = childParent.Last().DepartmentID; // get last departmentID
Departments tempDep = entites.Departments.Single(x => x.ID == lastDepID); // find as object
tempDep.level = childParent.Last().level + 1; // increase last level
childParent.Add(tempDep); // add to list
}
(Added another C1 to check 4th level)
Hope helps,

Below is the simple console project Program class code.
You can check with different IDs for the input parameter of the GetParentSet method.
class Program
{
static void Main(string[] args)
{
Program p = new Program();
var result= p.GetParentSet(6);
foreach(var a in result)
{
Console.WriteLine(string.Format("{0} {1} {2}",a.ID,a.Name,a.DepartmentId));
}
Console.Read();
}
private List<Department> GetParentSet(int id)
{
List<Department> result = new List<Department>(); //Result set
using (RamzDBEntities context = new RamzDBEntities())
{
var nodeList = context.Departments.Where(t=>t.ID<=id).ToList(); //Get All the the entries where ID is below or greater than the given to the list
var item = nodeList.Where(a => a.ID == id).SingleOrDefault(); //Get the default item for the given ID
result.Add(item); //Add it to the list. This will be the leaf of the tree
int size = nodeList.Count(); //Get the nodes count
for (int i = size; i >= 1;i--)
{
var newItem= nodeList.Where(j => j.ID == item.DepartmentId).SingleOrDefault(); //Get the immediate parent. This can be done by matching the leaf Department ID against the parent ID
if (item!=null && !result.Contains(newItem)) //If the selcted immediate parent item is not null and it is not alreday in the list
{
result.Add(newItem); //Add immediate parent item to the list
}
if (newItem.ID == 1) //If the immediate parent item ID is 1 that means we have reached the root of the tree and no need to iterate any more.
break;
item = newItem; //If the immediate parent item ID is not 1 that means there are more iterations. Se the immediate parent as the leaf and continue the loop to find its parent
}
}
return result; //return the result set
}
}
Code itself is self-explanatory. However below is the explanation. Hope this will help!
First all the entries with ID below or equal to the given ID is
assigned to a List
Then get the leaf of the tree and add it to the list named result. This is the first element of our result set
We iterate through the retrieved entries descending order. Get the immediate parent of the leaf by equating parent's ID to leaf's department ID
If this immediate parent is not null and its not already in the list add it to the list.
Make the immediate parent item as the leaf and continue the loop so that we can get the parent of the immediate parent.
continue this until we reach the root of the tree.
If the immediate parent ID is=1 that means we have reached the root of the tree and we can break the loop.

Since you generated the edmx, you have the code generated for your DbContext and for your Model Classes including Departments like on this screenshot.
You shouldn't modify them because they might (will) get overwritten by EF tools anyway on any model manipulation. Fortunately both classes are generated as partial so the creators thought about people wanting to customize it safely.
Example below is made for simplicity of implementation not for top performance. I assumed that the table containing Departments is not enormously big and the levels of nesting in hierarchy are not enormously deep.
Create a new Class (*.cs file) in your project and extend your auto-generated Departments class by your custom method or property:
using System;
using System.Collections.Generic;
using System.Linq;
namespace CustomEF.EFStuff
{
public partial class Departments
{
public List<Departments> Hierarchy {
get {
List<Departments> retVal = new List<Departments>();
retVal.Add(this);
using (YourAutoGeneratedContext ctx = new YourAutoGeneratedContext())
{
Departments tmp = this;
while(tmp.DepartmentID != null)
{
tmp = ctx.Departments.First(d => d.ID == tmp.DepartmentID);
retVal.Add(tmp);
}
}
return retVal;
}
private set { }
}
}
}
When you extend the partial class, make sure that you put it in the same namespace. In my case I named my project CustomEF and I've placed the edmx file in the EFStuff subfolder so the generator placed the auto generated class in the CustomEF.EFStuff namespace.
The example above will allow you to get the hierarchy for any Departments object e.g.
int level = 0;
foreach(Departments d in someDepartmentObject.Hierarchy)
{
Console.WriteLine(d.ID.ToString() + ", " + d.DepartmentID.ToString() + ", " + d.Name +", " +(level++).ToString());
}
If you also need to get the hierarchy from some code where you have an ID but not the object, you can additionally create another class (*.cs file) where you'll extend the auto-generated context.
using System.Collections.Generic;
using System.Linq;
namespace CustomEF.EFStuff
{
public partial class YourAutoGeneratedContext
{
public List<Departments> GetDepartmentHierarchy(int departmentId)
{
Departments mydep = this.Departments.FirstOrDefault(d => d.ID == departmentId);
if (mydep == null)
{
throw new System.Data.Entity.Core.ObjectNotFoundException("There is no department with ID = " + departmentId.ToString());
}
return mydep.Hierarchy;
}
}
}
Or in this case you might want to move the implementation to the Context class entirely, without extending the Departments class at all (and you wouldn't have to create an additional instance of your context, you'll have the this to use).
using System.Collections.Generic;
using System.Linq;
namespace CustomEF.EFStuff
{
public partial class YourAutoGeneratedContext
{
public List<Departments> GetDepartmentHierarchy(int departmentId)
{
Departments tmp = this.Departments.FirstOrDefault(d => d.ID == departmentId);
if (tmp == null)
{
throw new System.Data.Entity.Core.ObjectNotFoundException("There is no department with ID = " + departmentId.ToString());
}
List<Departments> retVal = new List<Departments>();
retVal.Add(tmp);
while (tmp.DepartmentID != null)
{
tmp = this.Departments.First(d => d.ID == tmp.DepartmentID);
retVal.Add(tmp);
}
return retVal;
}
}
}
As another unsophisticated use example:
YourAutoGeneratedContext ctx = new YourAutoGeneratedContext();
level = 0;
foreach (Departments currentHier in ctx.GetDepartmentHierarchy(10))
{
Console.WriteLine(currentHier.ID.ToString() + ", " + currentHier.DepartmentID.ToString() + ", " + currentHier.Name + ", " + (level++).ToString());
}
I don't know how much you can trust the data in the database. You might want to implement some checks including cross-referencing departments to prevent infinite loop.
Note that formally the term 'to extend a class' may apply to extension methods rather then to partial classes. I used this word from lack of better one. Extension methods would be something that you might want to use if, for some reason, you'd need your method/property returning EF native DbSet<> instead of the List<>. In such case you might want to take look at: https://shelakel.co.za/entity-framework-repository-pattern/

Example in EF6 to get all parents up to root node.
public class Department
{
[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Name { get; set; }
public int? ParentId { get; set; }
public virtual Department Parent { get; set; }
public virtual ICollection<Department> Children { get; set; }
private IList<Department> allParentsList = new List<Department>();
public IEnumerable<Department> AllParents()
{
var parent = Parent;
while (!(parent is null))
{
allParentsList.Add(parent);
parent = parent.Parent;
}
return allParentsList;
}
}

use include keyword.
_context.Invoices.Include(x => x.Users).Include(x => x.Food).ToList();

How to count total # of items in nested categories (self-referencing category table) [duplicate]

This question already has answers here:
Most efficient method of self referencing tree using Entity Framework
(6 answers)
Closed 7 years ago.
I am using C#, ASP.Net, Entity Framework, LINQ, Microsoft SQLServer
I have two tables
tblCategories
Id
Name
ParentId (parentId is the Id of another category in this table that is the parent of this one)
tblQuestion
Id
CategoryId
Etc.
So say my categories table contains
Programming (Id 1 ParentId null) - directly contains 10 questions
C# (Id 25 ParentId 1) – directly contains 5 questions
Interview Questions (Id 99 ParentId 25) - directly contains 2 questions
Variables (Id 100 ParentId 25) – directly contains 1 question
Networking (Id 2 Parent Id null)
I want to know how many questions exist for a each category, including its child categories.
In other words in this example 18 questions are in programming, 8 are in C#
Is it possible to do this in a query or do I need some kind of iterative loop called on each category?
such as db.categories.Where(something).count()
Here is my category class:
public class Category
{
[Key]
public int Id { get; set; }
[StringLength(40)]
public string Name { get; set; }
public int? ParentId { get; set; }
[JsonIgnore]
public virtual ICollection<Category> Children { get; set; }
[JsonIgnore]
public virtual Category Parent { get; set; }
[JsonIgnore]
public virtual ICollection<Question> Questions { get; set; }
}
then in OnModelCreating:
modelBuilder.Entity<Category>()
.HasMany(x => x.Children)
.WithOptional(y => y.Parent)
.HasForeignKey(z => z.ParentId)
.WillCascadeOnDelete(false);
there are several similar questions on StackOverflow, like this: Help with generating a report from data in a parent-children model and this linq aggregated nested count but I can't find one that is a good enough match and I can understand
To clarify, I want to know the number of questions in the child categories, not the number of child categories.

I am unsure as to what you want to accomplish, but as others pointed out it can't be accomplished by simple Linq.
If what you want is to get a total count of questions given a category: you need to:
var count = TotalQuestions(category1);
TotalQuestions method
public int TotalQuestions(Category category)
{
var totalQuestions = category.Questions.Count;
foreach (var innerCategory in category.Categories)
{
totalQuestions += TotalQuestions(innerCategory);
}
return totalQuestions;
//OR
//return category.Questions.Count + category.Categories.Sum(innerCategory => TotalQuestions(innerCategory));
}
If you want to have the total count of questions for each Category (including the count of its child categories) you need:
var counts = new Dictionary<Category, int>();
TotalQuestions(category1, counts);
2nd TotalQuestions method
private int TotalQuestions(Category category, Dictionary<Category, int> counts)
{
if (!counts.ContainsKey(category))
{
counts.Add(category, category.Questions.Count);
}
foreach (var innerCategory in category.Categories)
{
counts[category] += TotalQuestions(innerCategory, counts);
}
return counts[category];
}
Sample
For this sample data:
var category1 = new Category(1, "Cat1", null);
var category2 = new Category(1, "Cat2", category1);
var category3 = new Category(1, "Cat3", category2);
var category4 = new Category(1, "Cat4", category2);
var category5 = new Category(1, "Cat5", category3);
category1.Questions.Add(new Question("q1"));
category1.Questions.Add(new Question("q2"));
category1.Questions.Add(new Question("q3"));
category1.Questions.Add(new Question("q4"));
category2.Questions.Add(new Question("q1"));
category2.Questions.Add(new Question("q2"));
category2.Questions.Add(new Question("q3"));
category3.Questions.Add(new Question("q1"));
category3.Questions.Add(new Question("q2"));
category4.Questions.Add(new Question("q1"));
category5.Questions.Add(new Question("q1"));
category5.Questions.Add(new Question("q2"));
var count = TotalQuestions(category1);
MessageBox.Show(count.ToString());
var counts = new Dictionary<Category, int>();
TotalQuestions(category1, counts);
You Get:
count = 12
And in counts:
category1 => 12
category2 => 8
category3 => 4
category4 => 1
category5 => 2

Yes, you need a recursive method.
// Recursively counts the number of children of this parent
static int CountChildren(Category parent)
{
if (parent == null)
return 0;
if (parent.Children == null || !parent.Children.Any())
return 0;
return parent.Children.Count()
+ parent.Children.Sum(ch => CountChildren(ch));
}

You can't do such counting using only a simple linq query or only with fluent callings for the simple fact that you have a variable number of levels of iterations (the number of generations: parents, children, grandchildren, etc varies). Therefore, I would recommend creating a recursive method to count children:
static void RecursiveQuestionCount(Category cat, ref int count)
{
count += Questions.Count(); // this cat's questions.
foreach(var child in cat.Children)
{
RecursiveQuestionCount(child, ref count); // will add each child and so it goes...
}
}
The count result will be stored in the ref int count:
int catCount;
Foo.RecursiveQuestionCount(existingCategoryObj, catCount);
Console.WriteLine(catCount);

How do I count the number of child collection's items using LINQ Method Syntax?

Let's say I have a schema, representing Question entities. Each question can be voted up, voted down or, of course, not voted at all - just like here in StackOverflow. I want to get the number of voteups for a given user.
int number = (from q in userDbContext.Questions
from qv in q.QuestionVotes
where qv.IsVoteUp
select qv).Count();
I want to write the same query, but using Method Syntax. How do I do this with the same example?

You can use SelectMany:
userDbContext.Questions.SelectMany(x => x.QuestionVotes).Count(x => x.IsVoteUp);

This LINQ query demonstrates how to do that using 3 level structure tree > branch > leaf as an example.
So the code below gives you the number of the leaves from all branches of all trees (all or only colored with the given color):
public class Calculator
{
public int CountAllLeafsOn(List<Tree> trees, string сolor = null)
{
// Count the leafs (all from all branches of all trees, or only if they are colored with the provided color)
return сolor == null
? trees.Sum(tree => tree.Branches.Sum(branch => branch.Leaves.Count))
: trees.Sum(tree => tree.Branches.Sum(branch => branch.Leaves.Count(leaf => leaf.Color.Equals(сolor))));
}
}
public class Tree
{
public List<Branch> Branches { get; set; }
}
public class Branch
{
public List<Leaf> Leaves { get; set; }
}
public class Leaf
{
public string Color { get; set; }
}
Hope that helps.

It must work:
int number = userDbContext.Questions
.Select(x => x.QuestionVotes.Count(y => y.IsVoteUp))
.Sum();
It will get the count of filtered child items for each parent. Then Sum() will compute the sum of these values.

You can count children using Where like this:
foreach (YourCollectionType item in datagrid.Items)
{
var children = datagrid.ItemsSource.OfType<YourCollectionType>().Where(x => x.Item1 == item.Item1 && x.Item2 == item.Item2 && x.Item3 == item.Item3 && x.Item4 == item.Item4);
item.Results = children.Count();
Trace.TraceInformation(item.Results.ToString());
}

c# Searching List<t> inside another List<T>

How would I search for a value within a List<t> inside another List<t>
i.e.
//FooInner Class
public class FooInner {
public int FooInnerId { get; set; }
public String FooValue { get; set; }
}
//FooOuter Class
public class FooOuter {
public int FooOuterId { get; set; }
public List<FooInner> FooInnerCollection { get; set; }
}
If I just wanted to find a value in the outer class
// Working code
List<FooOuter> fooOuterCollection = GetSomeData();
var tmp = fooOuterCollection.Find( f => f.FooOuterId == 2 );
But what if I wanted the FooInner Object where FooOuterId == 2 and FooInnerCollection.FooInnerId == 4 (or contains depending how you look at it).
Hopefully that makes sense.

fooOuterCollection
.Where(outer => outer.FooOuterID == 2)
.SelectMany(outer => outer.FooInnerCollection)
.FirstOrDefault(fooInner => fooInner.FooInnerId == 4);
First we filter the outer objects to only include those with Id == 2
Then we use SelectMany to flatten out the multiple InnerCollections that we may find
Finally we filter based on the inner Id == 4

You can get inner object like this-
var temp= fooOuterCollection.Where(f => f.FooOuterId == 2)
.SelectMany(f => f.FooInnerCollection)
.FirstOrDefault(fi => fi.FooInnerId == 4));
If you need outer object, you need to use Any() extension method to see if inner list contains required element -
var temp = fooOuterCollection.FirstOrDefault(f => f.FooOuterId == 2 &&
f.FooInnerCollection.Any(fi => fi.FooInnerId == 4);

You could just use LINQ's query syntax:
var results = from o in outerList
where o.FooOuterId == 2
from i in o.FooInnerCollection
where i.FooInnerId == 4
select i;

Treeview with parent/child issue loading by status

I have the following table structure it might not be a correct structure but unfortunatly that's what I was given.
id | Name | Parent | Status
1 First 0 Active
2 Child 1 Active
3 2Child 2 Inactive
Logic:
Load Root by Parent = 0 and Status
OnPopulate load child by parent ID and status for every levels after root
my issue is if the status is "Inactive" and I want to see what options are inactive I can't because the first 2 options are active. What I need is to be able to view in my treeview all the levels down to the option that is Inactive or Active.
I have tried the following sql statement
select distinct
m.Id,
m.Name,
m.Parent,
m.[Status]
from mytable m
where m.Parent = 3 and m.[Status] = 'I'
union
select
Id,
Name,
Parent,
[Status]
from mytable
where ID in(select distinct
o.ID
from mytable o
where o.ID = 3 and o.[Status] = 'I') and Parent = 3
I have ran out of ideas in sql and coding to figure this out..hope someone could guide me in the right direction..thanks
Also tried this in code:
protected void mytree_TreeNodePopulate(object sender, TreeNodeEventArgs e)
{
//this is just a class that loads the values from db
MYList templist = new ListSyFamily();
templist.LoadAll();//(ddlStatus.SelectedValue, Convert.ToInt32(e.Node.Value));
foreach (temp temp in templist)
{
if (temp.Status == ddlStatus.SelectedValue && temp.Parent == Convert.ToInt32(e.Node.Value))
{
TreeNode child = new TreeNode();
child.Text = temp.Description;
child.Value = temp.Id.ToString();
if (child.ChildNodes.Count == 0)
child.PopulateOnDemand = true;
child.ToolTip = "Ver sub-opciones";
//child.SelectAction = TreeNodeSelectAction.SelectExpand;
child.CollapseAll();
e.Node.ChildNodes.Add(child);
}
}
}

Here is how we handle this.
Assume that you have a class called MyRecord to hold each row of data from the DB:
public class MyRecord
{
public int Id {get; set; }
public int ParentId {get; set; }
public string Name { get; set; }
public string Status { get; set; }
// The children of this node
public MyRecordCollection Children = new MyRecordCollection();
}
Then you have a collection type to hold these records indexed by their id:
public class MyRecordCollection : System.Collections.Generic.Dictionary<int, MyRecord>
{
}
Here is the code (retrieval from the DB not shown) to preprocess the records and then add them to the tree:
MyRecordCollection cAllRecords;
MyRecordCollection cParentRecords = new MyRecordCollection();
// This is a method that just loads the records
cAllRecords = LoadAllRecords();
// Cycle through each of the records
foreach (MyRecord oRecord in cAllRecords.Values)
{
if (oRecord.Id == 0)
{
// If the record is a parent record, add it to the list of parents
cParentRecords.Add(oRecord.Id, oRecord);
}
else
{
// Otherwise, add the current record to its parent's list of children
cAllRecords[oRecord.ParentId].Children.Add(oRecord.Id, oRecord);
}
}
AddNodesToTree(cParentRecords, this.treeView1.Nodes);
And finally, the recursive method for adding the records to the tree:
/// <summary>
/// A recursive method to add all of the records to the specified collection of nodes
/// </summary>
/// <param name="cRecords"></param>
/// <param name="cNodes"></param>
private void AddNodesToTree(MyRecordCollection cRecords, TreeNodeCollection cNodes)
{
foreach (MyRecord oRecord in cRecords.Values)
{
TreeNode oNode = new TreeNode();
oNode.Text = oRecord.Name;
oNode.Tag = oRecord;
cNodes.Add(oNode);
// Now add the node's children if any
if (oRecord.Children.Count != 0)
{
AddNodesToTree(oRecord.Children, oNode.Nodes);
}
}
}

Well, If I were you I would just load the entire table into memory into a simple Collection of a light DTO class and work out your treeview in C#. That seems a lot easier than to try a lot of options in SQL.