ADO.NET Cookbook

9.1. Filling a DataSet Asynchronously

Problem

Given some database queries that return large result sets and cause the calling application to be unresponsive, you need to make the application more responsive during the fill.

Solution

Create a background thread and use it to run a query to fill a DataSet. You can also fill a DataGrid object from a background thread.

The sample code contains one event handler and two methods:

Go Button.Click

Checks whether there is an existing background thread loading the DataSet. If the DataSet is not being loaded, a new thread is created invoking the AsyncFillDataSet( ) method to fill a DataSet. Otherwise, a message is displayed stating that the DataSet is currently being filled.

AsyncFillDataSet( )

This method loads a DataSet with the Orders and Order Details tables from the Northwind database. The BindDataSetToDataGrid( ) method is called asynchronously on the form’s thread to display the results. Finally, messages are displayed to indicate that the AsyncFillDataSet( ) method has started and when it has completed.

BindDataSetToDataGrid( )

This method binds the default view of the Orders table in the DataSet to the data grid on the form.

The C# code is shown in Example 9-1.

Example 9-1. File: AsynchronousFillForm.cs

// Namespaces, variables, and constants using System; using System.Configuration; using System.Threading; using System.Runtime.Remoting.Messaging; using System.Data; using System.Data.SqlClient; private delegate void BindDataSetToDataGridDelegate(DataSet ...