When I Clicked Row Button(Delete) In Grid View Then More Then One Row Are Deleting How Can I Solve This Problem ......Help

//here i m bind grid view from database in window form


private void Subjectseup()
{
gvsubjectsetup.DataSource = null;
try
{
string querystring = "SELECT * FROM dbo.Subjects";
DataTable datatable = Class1.Datatablebind(querystring);

gvsubjectsetup.AutoGenerateColumns = false;

//Set Columns Count
gvsubjectsetup.ColumnCount = 8;

//Add Columns
gvsubjectsetup.Columns[0].Name = "Subjectid";
gvsubjectsetup.Columns[0].HeaderText = "Subject Id";
gvsubjectsetup.Columns[0].DataPropertyName = "Subject_id";

gvsubjectsetup.Columns[1].HeaderText = "Subject Name";
gvsubjectsetup.Columns[1].Name = "Subject";
gvsubjectsetup.Columns[1].DataPropertyName = "Subject Name";

gvsubjectsetup.Columns[2].HeaderText = "Allow Class";
gvsubjectsetup.Columns[2].Name = "AllowClass";
gvsubjectsetup.Columns[2].DataPropertyName = "Allow Class";

gvsubjectsetup.Columns[3].Name = "SubjectType";
gvsubjectsetup.Columns[3].HeaderText = "Subject Type";
gvsubjectsetup.Columns[3].DataPropertyName = "Subject Type";

gvsubjectsetup.Columns[4].HeaderText = "Subject Valuation";
gvsubjectsetup.Columns[4].DataPropertyName = "Subject valuation";

gvsubjectsetup.Columns[5].HeaderText = "Create Date";
gvsubjectsetup.Columns[5].DataPropertyName = "Create date";

gvsubjectsetup.Columns[6].HeaderText = "Category";
gvsubjectsetup.Columns[6].DataPropertyName = "category";

// add a button column.
DataGridViewButtonColumn updatebutton = new DataGridViewButtonColumn();
// DataGridViewButtonColumn addsectionbutton = new DataGridViewButtonColumn();
DataGridViewButtonColumn deletbutton = new DataGridViewButtonColumn();

updatebutton.HeaderText = "Update Classes";
updatebutton.Text = "Update";
updatebutton.Name = "btnUpdate";

// addsectionbutton.HeaderText = "Add Section";
// addsectionbutton.Text = "Add Section";
// addsectionbutton.Name = "btnaddsection";

deletbutton.HeaderText = "Delete Classes";
deletbutton.Text = "Delete";
deletbutton.Name = "btnDelete";

updatebutton.UseColumnTextForButtonValue = true;
deletbutton.UseColumnTextForButtonValue = true;
// addsectionbutton.UseColumnTextForButtonValue = true;

gvsubjectsetup.Columns.Add(updatebutton);
// gvsubjectsetup.Columns.Add(addsectionbutton);
gvsubjectsetup.Columns.Add(deletbutton);

// ADD click event on button

gvsubjectsetup.CellClick += new DataGridViewCellEventHandler(gvsubjectsetup_click);
// gvsubjectsetup.DataSource = datatable;
gvsubjectsetup.DataSource = new BindingSource(datatable, null);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}








// here i m call this mathod on click "showdata " Button



void gvsubjectsetup_click(object sender, DataGridViewCellEventArgs e)
{
if ((e.RowIndex > 0) || (e.ColumnIndex == gvsubjectsetup.Columns["btnUpdate"].Index) || (e.ColumnIndex == gvsubjectsetup.Columns["btnDelete"].Index))
{
if (e.ColumnIndex == gvsubjectsetup.Columns["btnUpdate"].Index)
// MessageBox.Show("hi this is section"+ taskID);
{
int id ;
id = (Int32)gvsubjectsetup[0, e.RowIndex].Value;
string s =

above Show My Code.... i have no idea what i do for it please any one help me ...its urgent