无法绑定多部分标识符"System.Data.DataRowView"

Question

我有一个填充Combobox1的表，Combobox1应该填充Combobox2，这就是问题所在。这是我得到的例外

多部分标识符"System.Data. net"。无法绑定DataRowView。

代码:

    private void frm2_Load(object sender, EventArgs e)
    {
        //Populate Combobox1
        SqlDataAdapter da = new SqlDataAdapter("SELECT CategoryID, Name FROM Categories", clsMain.con);
        DataSet ds = new DataSet();
        da.Fill(ds);
        comboBox1.DataSource = ds.Tables[0];
        comboBox1.DisplayMember = "Name";
        comboBox1.ValueMember = "CategoryID";
    }
    private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        //populate Combobox2
        SqlDataAdapter da = new SqlDataAdapter("SELECT SubCategoryID, Name FROM SubCategories WHERE CategoryID=" + comboBox1.SelectedValue, clsMain.con);
        DataSet ds = new DataSet();
        da.Fill(ds);
        comboBox2.DataSource = ds.Tables[0];
        comboBox2.DisplayMember = "Name";
        comboBox2.ValueMember = "SubCategoryID";
    }

Answer 1

这是由于在第一个组合中填充数据时加载第二个组合框。
您可以通过以下方式避免此错误:
1. 使用 selectionchangecomcommitted 事件代替SelectedIndexChanged事件。
或
2. 分离选定的索引更改事件，填充组合框，再次将事件附加为:

private void frm2_Load(object sender, EventArgs e)
{
   //Detach event
   comboBox1.SelectedIndexChanged -= comboBox1_SelectedIndexChanged;
    //Populate Combobox1
    SqlDataAdapter da = new SqlDataAdapter("SELECT CategoryID, Name FROM Categories", clsMain.con);
    DataSet ds = new DataSet();
    da.Fill(ds);
    comboBox1.DataSource = ds.Tables[0];
    comboBox1.DisplayMember = "Name";
    comboBox1.ValueMember = "CategoryID";
   //Attach event again
    comboBox1.SelectedIndexChanged += comboBox1_SelectedIndexChanged;
}