C# C-向填充数据绑定的组合框添加值？

我试图将默认值添加到已填充数据源的组合框中。查看下图：

值是从oracle数据库自动添加的。现在我需要做的是再添加一个表示所有类别的默认值

以下是设计器代码：

this.comboBox2.DataBindings.Add(new System.Windows.Forms.Binding("SelectedValue", this.vRSTEPROBLEMABindingSource, "NAZIV", true));
        this.comboBox2.DataSource = this.vRSTEPROBLEMABindingSource1;
        this.comboBox2.DisplayMember = "NAZIV";
        this.comboBox2.FormattingEnabled = true;
        this.comboBox2.Location = new System.Drawing.Point(89, 51);
        this.comboBox2.Name = "comboBox2";
        this.comboBox2.Size = new System.Drawing.Size(173, 21);
        this.comboBox2.TabIndex = 4;
        this.comboBox2.Text = "Svi";
        this.comboBox2.ValueMember = "NAZIV";

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我找到了一个解决方案，无法向combobox添加数据绑定的项。您可以做的是将项目填入列表，然后将其添加到组合框中。下面是一个代码：

            // your connection string + open connection
            OracleConnection conn = new OracleConnection(global::IssueTracker.Properties.Settings.Default.ConnectionString);
            conn.Open();

            // data adapter
            OracleDataAdapter oa = new OracleDataAdapter("select naziv from vrsteproblema", conn);
            DataSet ds = new DataSet();
            oa.Fill(ds, "vrsteproblema");

            // put entries into a list
            List<string> comboNazivi = new List<string>();
            foreach (DataRow row in ds.Tables["vrsteproblema"].Rows)
            {
                comboNazivi.Add(row["naziv"].ToString());
            }

            // add custom entry
            comboBox2.Items.Add("Svi");
            // fill the rest from the list
            for (var i = 0; i < comboNazivi.Count; i++) {
                comboBox2.Items.Add(comboNazivi[i]);
            }

            // dont forget to close conn
            conn.Close();

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在将绑定源设置为数据源之前，需要向其添加默认值。