combobox选择而改变datagridviw绑定数据 不断添加数据不能请空

Question

 private void toolStripComboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (bdsInfo.DataSource != null)
            {
                DataTable dt = (DataTable)bdsInfo.DataSource;
                dt.Rows.Clear();
                bdsInfo.DataSource = dt;
                bdnInfo.BindingSource = bdsInfo;
                dgvInfo.DataSource = bdnInfo;
                
                loadview(toolStripComboBox1.Text.ToString());
            }
            else
            {
                loadview(toolStripComboBox1.Text.ToString());
            }
我选择一次添加一次 不能清空？？？？？？？？

Answer 1

        if (!this.IsPostBack)
        {
在这里面面调用
          }
把它写成方法再调用