第一次查询正常，第二次查询就会多查询数据一次，第三次再点击按钮查询的时候又会查询三次，奇怪了！那为给麻烦看看原因！！
private void btnQuery_Click(object sender, EventArgs e)
{
dataG_rsj.Rows.Clear();
Bw.WorkerSupportsCancellation = true;
Bw.WorkerReportsProgress = true;
Bw.DoWork += new DoWorkEventHandler(Add);//绑定事件
Bw.ProgressChanged += new ProgressChangedEventHandler(Progress);
Bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(End);
Bw.RunWorkerAsync();

}
BackgroundWorker Bw = new BackgroundWorker();


public void Add(object sender, DoWorkEventArgs e)
{
string strSql = "select * from Sale_Table";
OracleDataReader reader = App.DBE.ExecReader(strSql);
object[] objcell = new object[34];
if (reader.HasRows)
{
while (reader.Read())
{
if ((Bw.CancellationPending == true))
{
e.Cancel = true;

break;
}
else
{
reader.GetValues(objcell);
Bw.ReportProgress(3, objcell);
Thread.Sleep(15);

}

}

}
reader.Close();

}
public void Progress(object sender, ProgressChangedEventArgs e)
{
object[] objcell = e.UserState as object[];
this.dataG_rsj.Rows.Add(objcell);
label3.Text = DateTime.Now.ToLongTimeString();
}

问题是现在点击按钮后，第一次查询正常，第二次查询就会多查询数据一次，第三次再点击按钮查询的时候又会查询三次，奇怪了！那为给麻烦看看原因！！

[解决办法]

Bw.WorkerSupportsCancellation = true;
Bw.WorkerReportsProgress = true;
Bw.DoWork += new DoWorkEventHandler(Add);//绑定事件
Bw.ProgressChanged += new ProgressChangedEventHandler(Progress);
Bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(End);