实时更新DataGridView 合计值

public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
dataGridView1.DataSourceChanged += new EventHandler(dataGridView1_DataSourceChanged);
dataGridView1.CellValueChanged += new DataGridViewCellEventHandler(dataGridView1_CellValueChanged);
}

private void Form1_Load(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection("Data Source=.;Initial Catalog=pubs;Integrated Security=True");
using (SqlDataAdapter da = new SqlDataAdapter("select * from jobs", conn))
{
DataTable dt = new DataTable();
da.Fill(dt);
dataGridView1.DataSource = dt;
}
dataGridView1.RowsAdded += new DataGridViewRowsAddedEventHandler(dataGridView1_RowsAdded);
dataGridView1.RowsRemoved += new DataGridViewRowsRemovedEventHandler(dataGridView1_RowsRemoved);
}

private void dataGridView1_DataSourceChanged(object sender, EventArgs e)
{
TextSum();
}

private void TextSum()
{
//throw new Exception("The method or operation is not implemented.");
int x1 = 0;
int x2 = 0;
foreach (DataGridViewRow dr in dataGridView1.Rows)
{
if (!IsNullOrEmpty(dr.Cells["min_lvl"].Value))
x1 += Convert.ToInt32(dr.Cells["min_lvl"].Value.ToString());

if (!IsNullOrEmpty(dr.Cells["max_lvl"].Value))
x2 += Convert.ToInt32(dr.Cells["max_lvl"].Value.ToString());
}
textBox1.Text = x1.ToString();
textBox2.Text = x2.ToString();
}

private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
dataGridView1_DataSourceChanged(null, null);
}

private void dataGridView1_RowsAdded(object sender, DataGridViewRowsAddedEventArgs e)
{
dataGridView1_DataSourceChanged(null, null);
}

private void dataGridView1_RowsRemoved(object sender, DataGridViewRowsRemovedEventArgs e)
{
dataGridView1_DataSourceChanged(null, null);
}

private bool IsNullOrEmpty(object value)
{
if (value != null)
return value.ToString() == string.Empty;
return true;
}

private bool IsNullOrWhite(object value)
{
if (value != null)
return value.ToString().Trim() == string.Empty;
return true;
}
}