.NET & XML

Populating a DataSet

The DataSet is now ready to use just as if you had created it procedurally. You can create new rows in each of its tables, using the DataTable.NewRow( ) and DataTable.Rows.Add( ) methods, as shown in Example 11-5.

Example 11-5. Populating the DataSet

using System;
using System.Data;

public class CreateData {
  public static void Main(string [ ] args) {

    DataSet dataSet = new DataSet( );
    dataSet.ReadXmlSchema("Coupons.xsd");
    
    DataTable couponsTable = dataSet.Tables["coupons"];

    DataRow couponRow = couponsTable.NewRow( );
    couponRow["coupon_code"] = "763FF";
    couponRow["discount_amount"] = 0.5;
    couponRow["discount_type"] = DiscountType.Fixed;
    couponRow["expiration_date"] = new DateTime(2002,12,31);
    couponsTable.Rows.Add(couponRow);

    dataSet.WriteXml("Coupons.xml");
  }
}

Some important highlights of this program are listed below. First, a new DataSet instance is created, and its structure is populated with the saved Coupons.xsd schema:

DataSet dataSet = new DataSet( );
dataSet.ReadXmlSchema("Coupons.xsd");

Next, the “coupons” table is retrieved using the DataTableCollection’s string indexer:

DataTable couponsTable = dataSet.Tables["coupons"];

You can only create a new row using the DataTable’s NewRow( ) factory method. This is because the columns must be populated according to the database schema stored in the DataTable. Note that the NewRow( ) method does not actually add the new DataRow to the DataTable; that happens later:

DataRow couponRow = couponsTable.NewRow( );

Now ...