c# - DataSource.Relations.Add 不起作用

Question

我有以下代码，我尝试在基于 3 个表的单个数据集中创建 2 个关系。如果我使用 datasource.Relations.Add(relationname) 运行代码，表单将不会显示任何内容。如果我评论这一行，它将向我显示信息，但我需要定义这 2 个关系，因为我在 2 个单独的组合框中使用该信息。

public void Fill_DataSource()
{
    SqlConnection conn = new SqlConnection(ConfigurationManager
                    .ConnectionStrings["SRDBConnection"]
                    .ConnectionString);
    try
    {
        //Open the connection
        conn.Open();
        //Create the dataset
        ds = new DataSet();
        //Fill the dataset with the base table, Roles
        SqlDataAdapter daRoles = new SqlDataAdapter(new SqlCommand("select *" +
                                                                  "from Roles", 
                                                                   conn));
        daRoles.TableMappings.Add("Table", "Roles");
        daRoles.Fill(ds);
        //Fill the dataset with the joining table, SystemRoles
        SqlDataAdapter daSysRoles = new SqlDataAdapter(new SqlCommand("select *" + 
                                                      "from SystemRoles", conn));
        daSysRoles.TableMappings.Add("Table", "SysRoles");
        daSysRoles.Fill(ds);
        //Fill the dataset with the joining table, BusinessGroups
        SqlDataAdapter daBGs = new SqlDataAdapter(new SqlCommand("select *" + 
                                                       "from BusinessGroups", conn));
        daBGs.TableMappings.Add("Table", "BusinessGroups");
        daBGs.Fill(ds);
        // Show created Tablenames within the Dataset
        string myMessage = "Table Mappings: ";
        for (int i = 0; i < ds.Tables.Count; i++)
        {
            myMessage += i.ToString() + " "
            + ds.Tables[i].ToString() + " ";
        }
        // Establish the Relationship "RolesBGs" 
        // between  Roles>---<BusinessGroups
        DataRelation relRolesBGs;
        DataColumn colRoleId1;
        DataColumn colBGId;
        colRoleId1 = ds.Tables["Roles"].Columns["BGId"];
        colBGId = ds.Tables["BusinessGroups"].Columns["BGId"];
        relRolesBGs = new DataRelation("relRolesBGs", colRoleId1, colBGId);
        // If I uncomment the following line the form will no longer display anything
        // and also the debugger will skip any following breaking points after it
        //ds.Relations.Add(relRolesBGs);
        // Establish the Relationship "RolesSysRoles" 
        // between  Roles>---<SystemRoles
        //DataRelation relRolesSysRoles;
        //DataColumn colRoleId2;
        //DataColumn colSysRoleId;
        //colRoleId2 = ds.Tables["Roles"].Columns["SysRoleId"];
        //colSysRoleId = ds.Tables["SystemRoles"].Columns["SysRoleId"];
        //relRolesSysRoles = new DataRelation("relRolesSysRoles", colRoleId2, colSysRoleId);
        //ds.Relations.Add(relRolesSysRoles);
        // Show created Relations within the Dataset
        myMessage += "Relation Mappings: ";
        for (int i = 0; i < ds.Relations.Count; i++)
        {
            myMessage += i.ToString() + " "
            + ds.Relations[i].ToString() + " ";
        }
        textBox4.Text = myMessage;
        dsView = ds.DefaultViewManager;
        //Databinding for the Sys Role ComboBox
        //cbSysRole.DataSource = dsView;
        //cbSysRole.DisplayMember = "SysRoles.Name";
        //cbSysRole.ValueMember = "SysRoles.SysRoleId";
        //Databinding for the Business Group ComboBox
        //cbBG.DataSource = dsView;
        //cbBG.DisplayMember = "BusinessGroups.Name";
        //cbBG.ValueMember = "BusinessGroups.BGId";
        //BGbindSource.DataSource = ds.Tables[0];
        ///bindingNavigator1.BindingSource = BGbindSource;
        //RoleCode
        tbRoleCode.DataBindings.Clear();
        tbRoleCode.DataBindings.Add(new Binding("Text", dsView, "Roles.RoleCode",
                                     true, DataSourceUpdateMode.OnPropertyChanged));
        //RoleName
        tbRoleName.DataBindings.Clear();
        tbRoleName.DataBindings.Add(new Binding("Text", dsView, "Roles.RoleName",
                                     true, DataSourceUpdateMode.OnPropertyChanged));
        //RoleDesc
        tbRoleDesc.DataBindings.Clear();
        tbRoleDesc.DataBindings.Add(new Binding("Text", dsView, 
            "Roles.RoleDescription", true, DataSourceUpdateMode.OnPropertyChanged));
        //RoleId
        tbRoleId.DataBindings.Clear();
        tbRoleId.DataBindings.Add(new Binding("Text", dsView, "Roles.RoleId", 
                        true, DataSourceUpdateMode.OnPropertyChanged));
    }
    catch (Exception)
    {
        toolStripStatusLabel3.Text = "Database Is Offline or the Connection is not set correctly!";
    }
    finally
    {
        conn.Close();
    }
}
public Roles()
{
    InitializeComponent();
    Fill_DataSource();
}

正如代码注释中提到的，如果我取消注释并在它之后甚至在它上面创建断点，调试器将跳过这些，我只会得到一个空表单。我不明白那里有什么问题。任何帮助将不胜感激！！！

谢谢！