ADO.NET最佳实践（下）[9]

  custda.updatecommand = new sqlcommand("update customers (customerid, companyname) values(@customerid, @companyname) " +

                                        "where customerid = @oldcustomerid and companyname = @oldcompanyname", nwindconn);

  custda.updatecommand.parameters.add("@customerid", sqldbtype.nchar, 5, "customerid");

  custda.updatecommand.parameters.add("@companyname", sqldbtype.nvarchar, 30, "companyname");

  // pass the original values to the where clause parameters.

  sqlparameter myparm;

  myparm = custda.updatecommand.parameters.add("@oldcustomerid", sqldbtype.nchar, 5, "customerid");

  myparm.sourceversion = datarowversion.original;

  myparm = custda.updatecommand.parameters.add("@oldcompanyname", sqldbtype.nvarchar, 30, "companyname");

  myparm.sourceversion = datarowversion.original;

  // add the rowupdated event handler.

  custda.rowupdated += new sqlrowupdatedeventhandler(onrowupdated);

  dataset custds = new dataset();

  custda.fill(custds, "customers");

  // modify the dataset contents.

  custda.update(custds, "customers");

  foreach (datarow myrow in custds.tables["customers"].rows)

  {