// Put the next line into the Declarations section.
   private System.Data.DataSet dataSet;

   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.
       dataGrid1.SetDataBinding(dataSet,"ParentTable");
   }

//引入命名空间
using System;
using System.Data;

class Program {
   static void Main(string[] args) {
      // Create two tables and add them into the DataSet
      DataTable orderTable = CreateOrderTable();
      DataTable orderDetailTable = CreateOrderDetailTable();
      DataSet salesSet = new DataSet();
      salesSet.Tables.Add(orderTable);
      salesSet.Tables.Add(orderDetailTable);

      // Set the relations between the tables and create the related constraint.
      salesSet.Relations.Add("OrderOrderDetail", orderTable.Columns["OrderId"], orderDetailTable.Columns["OrderId"], true);

      Console.WriteLine("After creating the foreign key constriant, you will see the following error if inserting order detail with the wrong OrderId: ");
      try {
         DataRow errorRow = orderDetailTable.NewRow();
         errorRow[0] = 1;
         errorRow[1] = "O0007";
         orderDetailTable.Rows.Add(errorRow);
      } catch (Exception e) {
         Console.WriteLine(e.Message);
      }
      Console.WriteLine();

      // Insert the rows into the table
      InsertOrders(orderTable);
      InsertOrderDetails(orderDetailTable);

      Console.WriteLine("The initial Order table.");
      ShowTable(orderTable);

      Console.WriteLine("The OrderDetail table.");
      ShowTable(orderDetailTable);

      // Use the Aggregate-Sum on the child table column to get the result.
      DataColumn colSub = new DataColumn("SubTotal", typeof(Decimal), "Sum(Child.LineTotal)");
      orderTable.Columns.Add(colSub);

      // Compute the tax by referencing the SubTotal expression column.
      DataColumn colTax = new DataColumn("Tax", typeof(Decimal), "SubTotal*0.1");
      orderTable.Columns.Add(colTax);

      // If the OrderId is 'Total', compute the due on all orders; or compute the due on this order.
      DataColumn colTotal = new DataColumn("TotalDue", typeof(Decimal), "IIF(OrderId='Total',Sum(SubTotal)+Sum(Tax),SubTotal+Tax)");
      orderTable.Columns.Add(colTotal);

      DataRow row = orderTable.NewRow();
      row["OrderId"] = "Total";
      orderTable.Rows.Add(row);

      Console.WriteLine("The Order table with the expression columns.");
      ShowTable(orderTable);

      Console.WriteLine("Press any key to exit.....");
      Console.ReadKey();
   }

   private static DataTable CreateOrderTable() {
      DataTable orderTable = new DataTable("Order");

      // Define one column.
      DataColumn colId = new DataColumn("OrderId", typeof(String));
      orderTable.Columns.Add(colId);

      DataColumn colDate = new DataColumn("OrderDate", typeof(DateTime));
      orderTable.Columns.Add(colDate);

      // Set the OrderId column as the primary key.
      orderTable.PrimaryKey = new DataColumn[] { colId };

      return orderTable;
   }

   private static DataTable CreateOrderDetailTable() {
      DataTable orderDetailTable = new DataTable("OrderDetail");

      // Define all the columns once.
      DataColumn[] cols ={
                                  new DataColumn("OrderDetailId",typeof(Int32)),
                                  new DataColumn("OrderId",typeof(String)),
                                  new DataColumn("Product",typeof(String)),
                                  new DataColumn("UnitPrice",typeof(Decimal)),
                                  new DataColumn("OrderQty",typeof(Int32)),
                                  new DataColumn("LineTotal",typeof(Decimal),"UnitPrice*OrderQty")
                              };

      orderDetailTable.Columns.AddRange(cols);
      orderDetailTable.PrimaryKey = new DataColumn[] { orderDetailTable.Columns["OrderDetailId"] };
     return orderDetailTable;
   }

   private static void InsertOrders(DataTable orderTable) {
      // Add one row once.
      DataRow row1 = orderTable.NewRow();
      row1["OrderId"] = "O0001";
      row1["OrderDate"] = new DateTime(2013, 3, 1);
      orderTable.Rows.Add(row1);

      DataRow row2 = orderTable.NewRow();
      row2["OrderId"] = "O0002";
      row2["OrderDate"] = new DateTime(2013, 3, 12);
      orderTable.Rows.Add(row2);

      DataRow row3 = orderTable.NewRow();
      row3["OrderId"] = "O0003";
      row3["OrderDate"] = new DateTime(2013, 3, 20);
      orderTable.Rows.Add(row3);
   }

   private static void InsertOrderDetails(DataTable orderDetailTable) {
      // Use an Object array to insert all the rows .
      // Values in the array are matched sequentially to the columns, based on the order in which they appear in the table.
      Object[] rows = {
                                 new Object[]{1,"O0001","Mountain Bike",1419.5,36},
                                 new Object[]{2,"O0001","Road Bike",1233.6,16},
                                 new Object[]{3,"O0001","Touring Bike",1653.3,32},
                                 new Object[]{4,"O0002","Mountain Bike",1419.5,24},
                                 new Object[]{5,"O0002","Road Bike",1233.6,12},
                                 new Object[]{6,"O0003","Mountain Bike",1419.5,48},
                                 new Object[]{7,"O0003","Touring Bike",1653.3,8},
                             };

      foreach (Object[] row in rows) {
         orderDetailTable.Rows.Add(row);
      }
   }

   private static void ShowTable(DataTable table) {
      foreach (DataColumn col in table.Columns) {
         Console.Write("{0,-14}", col.ColumnName);
      }
      Console.WriteLine();

      foreach (DataRow row in table.Rows) {
         foreach (DataColumn col in table.Columns) {
            if (col.DataType.Equals(typeof(DateTime)))
               Console.Write("{0,-14:d}", row[col]);
            else if (col.DataType.Equals(typeof(Decimal)))
               Console.Write("{0,-14:C}", row[col]);
            else
               Console.Write("{0,-14}", row[col]);           
         }
         Console.WriteLine();
      }
      Console.WriteLine();
   }
}