private void dgv_productList_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
if (e.ColumnIndex != 0 || e.RowIndex == -1) return;
for (int i = 0; i < dgv_productList.Rows.Count; i++)
{
DataGridViewCheckBoxCell checkcell = (DataGridViewCheckBoxCell)dgv_productList.Rows[i].Cells[0];
if(e.RowIndex==i){
checkcell.Value = !Convert.ToBoolean(checkcell.Value);
}else{
checkcell.Value=false;
}
}
}