Data Table in c#

public partial class Form1 : Form { DataSet dataSet; public Form1() { InitializeComponent(); } private void MakeDataTables() { // Run all of the functions. MakeParentTable(); MakeChildTable(); MakeDataRelation(); BindToDataGrid(); } private void MakeParentTable() { // Create a new DataTable. System.Data.DataTable table = new DataTable("ParentTable"); // Declare variables for DataColumn and DataRow objects. DataColumn column; DataRow row; // Create new DataColumn, set DataType, // ColumnName and add to DataTable. column = new DataColumn(); column.DataType = System.Type.GetType("System.Int32"); column.ColumnName = "id"; column.ReadOnly = true; column.Unique = true; // Add the Column to the DataColumnCollection. table.Columns.Add(column); // Create second column. column = new DataColumn(); column.DataType = System.Type.GetType("System.String"); column.ColumnName = "ParentItem"; column.AutoIncrement = false; column.Caption = "ParentItem"; column.ReadOnly = false; column.Unique = false; // Add the column to the table. table.Columns.Add(column); // Make the ID column the primary key column. DataColumn[] PrimaryKeyColumns = new DataColumn[1]; PrimaryKeyColumns[0] = table.Columns["id"]; table.PrimaryKey = PrimaryKeyColumns; // Instantiate the DataSet variable. dataSet = new DataSet(); // Add the new DataTable to the DataSet. dataSet.Tables.Add(table); // Create three new DataRow objects and add // them to the DataTable for (int i = 0; i <= 2; i++) { row = table.NewRow(); row["id"] = i; row["ParentItem"] = "ParentItem " + i; table.Rows.Add(row); } } private void MakeChildTable() { // Create a new DataTable. DataTable table = new DataTable("childTable"); DataColumn column; DataRow row; // Create first column and add to the DataTable. column = new DataColumn(); column.DataType = System.Type.GetType("System.Int32"); column.ColumnName = "ChildID"; column.AutoIncrement = true; column.Caption = "ID"; column.ReadOnly = true; column.Unique = true; // Add the column to the DataColumnCollection. table.Columns.Add(column); // Create second column. column = new DataColumn(); column.DataType = System.Type.GetType("System.String"); column.ColumnName = "ChildItem"; column.AutoIncrement = false; column.Caption = "ChildItem"; column.ReadOnly = false; column.Unique = false; table.Columns.Add(column); // Create third column. column = new DataColumn(); column.DataType = System.Type.GetType("System.Int32"); column.ColumnName = "ParentID"; column.AutoIncrement = false; column.Caption = "ParentID"; column.ReadOnly = false; column.Unique = false; table.Columns.Add(column); dataSet.Tables.Add(table); // Create three sets of DataRow objects, // five rows each, and add to DataTable. for (int i = 0; i <= 4; i++) { row = table.NewRow(); row["childID"] = i; row["ChildItem"] = "Item " + i; row["ParentID"] = 0; table.Rows.Add(row); } for (int i = 0; i <= 4; i++) { row = table.NewRow(); row["childID"] = i + 5; row["ChildItem"] = "Item " + i; row["ParentID"] = 1; table.Rows.Add(row); } for (int i = 0; i <= 4; i++) { row = table.NewRow(); row["childID"] = i + 10; row["ChildItem"] = "Item " + i; row["ParentID"] = 2; table.Rows.Add(row); } } private void MakeDataRelation() { // DataRelation requires two DataColumn // (parent and child) and a name. DataColumn parentColumn = dataSet.Tables["ParentTable"].Columns["id"]; DataColumn childColumn = dataSet.Tables["ChildTable"].Columns["ParentID"]; DataRelation relation = new DataRelation("parent2Child", parentColumn, childColumn); dataSet.Tables["ChildTable"].ParentRelations.Add(relation); } private void BindToDataGrid() { // Instruct the DataGrid to bind to the DataSet, with the // ParentTable as the topmost DataTable. DataGrid dg1 = new DataGrid(); dg1.Width = 500; dg1.Height = 200; this.Controls.Add(dg1); dg1.SetDataBinding(dataSet, "ParentTable"); } private void Form1_Load(object sender, EventArgs e) { MakeDataTables(); } }