Hi Lance,
Since you have created a parent-child relationship on the self referencing
data table, you can call the DataRow.GetChildRows method to get the
immediate child rows of the specified parent data row and then make use of
the recursive algorithm to get the count of all the child rows.
The following is a sample.
public partial class Form1 : Form
{
DataSet ds = new DataSet();
DataTable table = new DataTable();
private void Form1_Load(object sender, EventArgs e)
{
// add three data columns into the data table
DataColumn col = new DataColumn("ID", typeof(int));
table.Columns.Add(col);
col = new DataColumn("CatName");
table.Columns.Add(col);
col = new DataColumn("ParentID",typeof(int));
table.Columns.Add(col);
ds.Tables.Add(table);
// add a parent-child relationship into the data set
DataRelation rel = new DataRelation("relation1",
table.Columns[0], table.Columns[2], false);
ds.Relations.Add(rel);
// add some rows into the data table
DataRow row = ds.Tables[0].NewRow();
row[0] = 1;
row[1] = "Cat1";
row[2] = 0;
ds.Tables[0].Rows.Add(row);
row = ds.Tables[0].NewRow();
row[0] = 2;
row[1] = "SubCat1";
row[2] = 1;
ds.Tables[0].Rows.Add(row);
row = ds.Tables[0].NewRow();
row[0] = 3;
row[1] = "SubCat2";
row[2] = 1;
ds.Tables[0].Rows.Add(row);
row = ds.Tables[0].NewRow();
row[0] = 4;
row[1] = "SSubCat1";
row[2] = 3;
ds.Tables[0].Rows.Add(row);
row = ds.Tables[0].NewRow();
row[0] = 5;
row[1] = "SSubCat2";
row[2] = 3;
ds.Tables[0].Rows.Add(row);
row = ds.Tables[0].NewRow();
row[0] = 6;
row[1] = "SubCat3";
row[2] = 1;
ds.Tables[0].Rows.Add(row);
row = ds.Tables[0].NewRow();
row[0] = 7;
row[1] = "Cat2";
row[2] = 0;
ds.Tables[0].Rows.Add(row);
row = ds.Tables[0].NewRow();
row[0] = 8;
row[1] = "SubCat1";
row[2] = 7;
ds.Tables[0].Rows.Add(row);
row = ds.Tables[0].NewRow();
row[0] = 9;
row[1] = "SubCat2";
row[2] = 7;
ds.Tables[0].Rows.Add(row);
foreach (DataRow datarow in ds.Tables[0].Rows)
{
Console.WriteLine(datarow[0].ToString() + " " +
datarow[1].ToString() + "(" + GetChildCount(datarow).ToString() + ")");
}
}
// get the count of all the child rows of a specified data row
private int GetChildCount(DataRow row)
{
int count = 0;
DataRow[] childrows =
row.GetChildRows(ds.Relations["relation1"]);
foreach (DataRow datarow in childrows)
{
count++;
count += GetChildCount(datarow);
}
return count;
}
}
Hope this helps.
If you have anything unclear, please feel free to let me know.
Sincerely,
Linda Liu
Microsoft Online Community Support
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