C#

public void FillCombo()
{
   DataTable dt = new DataTable();
   StrSql = "select Level_Id,Level_Name from UserLevel";
   StrSql += " where Level_Id = '2'";
   dt = qry.FillDataSet(StrSql).Tables[0];
   if (dt.Rows.Count > 0)
   {
      MessageBox.Show("More than one row");
   }
   AddChildCombo(2, ref dt);
   this.cmbParentLevel.DataSource = dt;
   this.cmbParentLevel.DisplayMember = "Level_Name";
   this.cmbParentLevel.ValueMember = "Level_Id"; 
}

private void AddChildCombo(int objid,ref DataTable Table)
{
   DataTable Objdt; 
   int Objval; 
   StrSql = "select Level_Id,Level_Name from UserLevel";
   StrSql += " where Parent_LevelId = " + objid + "";
   Objdt = qry.FillDataSet(StrSql).Tables[0];
   for ( int i = 0; i <= Objdt.Rows.Count - 1; i++)
   { 
      Table.ImportRow(Objdt.Rows[i]); 
      Objval = Convert.ToInt32(Objdt.Rows[i].ItemArray[0]);
      AddChildCombo(Objval, ref Objdt);
   }
}

Data
Level_Id ParentId Level_Name
-----------------------------
2        NULL     Account
3        2        Perment
4        2        Tempray
11       NULL     Sales
12       11       tttttt
13       11       pppp
14       12       qqqqq
15       13       jjjjj
16       15       asd
17       16       sasda
20       17       fffff
23       NULL     Purchase
28       23       Pur1
30       20       qqqqqqq
31       14       aaaa
32       15       bbbbbbbb
33       32       iiiiiii
34       3        Company Employees
35       4        Contract Base Employee

public void FillCombo()
{
   DataTable dt = new DataTable();
   string sql = "select Level_Id, Level_Name from UserLevel"
              + " where Level_Name = 'Sales'";
   dt = qry.FillDataSet(sql).Tables[0];
   if (dt.Rows.Count > 1)
   {
      MessageBox.Show("Problem: More than one row");
   }
   AddChildCombo((int)dt.Rows[0]["Level_Id"], ref dt);
   this.cmbParentLevel.DataSource = dt;
   this.cmbParentLevel.DisplayMember = "Level_Name";
   this.cmbParentLevel.ValueMember = "Level_Id";
}
private void AddChildCombo(int parentLevelId,ref DataTable Table)
{
   DataTable childTable;
   string sql = "select Level_Id,Level_Name from UserLevel"
              + " where Parent_LevelId = " + parentLevelId + "";
   childTable = qry.FillDataSet(sql).Tables[0];
   <code>-- Check with debugger that rows are correctly</code>
   for ( int i = 0; i <= childTable.Rows.Count - 1; i++)
   {
      Table.ImportRow(childTable.Rows[i]);
      AddChildCombo((int)childTable.Rows[i]["Level_Id"], ref Table);
   }
}

aajignesh wrote:

In That the Data Will come is proper but Sir that Are Duplicate in to the combobox

public void FillCombo()
{
   <code>this.cmbParentLevel.DataSource = null;</code>
   DataTable dt;
   strinf sql = "select Level_Id, Level_Name from UserLevel"
              + " where Level_Name = 'Sales'";
   dt = qry.FillDataSet(sql).Tables[0];
   if (dt.Rows.Count > 1)
   {
      MessageBox.Show("Problem: More than one row");
   }
   AddChildCombo((int)dt.Rows[0]["Level_Id"], ref dt);
   <code>this.cmbParentLevel.Items.Clear(); </code>
   this.cmbParentLevel.DataSource = dt;
   this.cmbParentLevel.DisplayMember = "Level_Name";
   this.cmbParentLevel.ValueMember = "Level_Id";
}

aajignesh wrote:

My one Friend Sid that that's to fillcombo with use Recursion is not give Proper Result and also say that that it is not proper way.

aajignesh wrote:

So if U know to the Other Way to Fill Combo so Please Tell Me That's Request Please

aajignesh wrote:

If Sir U Have Any Other Idea to FillCombo so Plese Tell Me Please

private void Form2_Load(object sender, EventArgs e) {
   FillCombo();
}

private DataTable GetDataTable() {
   DataTable data = new DataTable();

   data.Columns.Add("Id", typeof(int));
   data.Columns.Add("ParentId", typeof(int));
   data.Columns.Add("LevelName", typeof(string));

   data.Rows.Add(2, null, "Account");
   data.Rows.Add(3, 2, "Perment");
   data.Rows.Add(4, 2, "Tempray");
   data.Rows.Add(11, null, "Sales");
   data.Rows.Add(12, 11, "tttttt");
   data.Rows.Add(13, 11, "pppp");
   data.Rows.Add(14, 12, "qqqqq");
   data.Rows.Add(15, 13, "jjjjj");
   data.Rows.Add(16, 15, "asd");
   data.Rows.Add(17, 16, "sasda");
   data.Rows.Add(20, 17, "fffff");
   data.Rows.Add(23, null, "Purchase");
   data.Rows.Add(28, 23, "Pur1");
   data.Rows.Add(30, 20, "qqqqqqq");
   data.Rows.Add(31, 14, "aaaa");
   data.Rows.Add(32, 15, "bbbbbbbb");
   data.Rows.Add(33, 32, "iiiiiii");
   data.Rows.Add(34, 3, "Company Employees");
   data.Rows.Add(35, 4, "Contract Base Employee");

   return data;
}

public void FillCombo() {
   DataTable dt = GetDataTable().Clone();
   DataRow startRow = GetDataTable().Select("LevelName = 'Sales'")[0];
   AddChildren((int)startRow["Id"], ref dt);
   this.cmbTest.DisplayMember = "LevelName";
   this.cmbTest.ValueMember = "Id";
   this.cmbTest.DataSource = dt;
}

private void AddChildren(int parentId, ref DataTable TableToFill) {
   DataRow[] children = GetDataTable().Select("ParentId = " + parentId.ToString());
   for ( int i = 0; i <= children.Length- 1; i++) {
      TableToFill.ImportRow(children[i]);
      AddChildren((int)children[i]["Id"], ref TableToFill);
   }
}