vb.net Combobox在绑定数据的基础上添加一个"全部"选项

如果数据源是从数据库里读出来的，就直接在数据库里加个“0-全部”就行了吧

已解决，效果非常好。谢谢各位的关注！愿与大家分享。
        Dim MyConnection As New System.Data.OleDb.OleDbConnection(MySQLConnectionString)
        MyConnection.Open()
        Dim MySQL As String = "select distinct 主题 from 日记 ORDER BY 主题 DESC"
        Dim MyAdapter As New OleDbDataAdapter(MySQL, MyConnection)
        Dim MyDepartmentTable As New System.Data.DataTable()
        MyAdapter.Fill(MyDepartmentTable)
      
        Dim dr As DataRow = MyDepartmentTable.NewRow()
        dr("主题") = "(全选)"
        MyDepartmentTable.Rows.InsertAt(dr, 0)
      
        Me.主题ComboBox1.DataSource = MyDepartmentTable
        Me.主题ComboBox1.DisplayMember = "主题"
        Me.主题ComboBox1.ValueMember = "主题"
        If (MyConnection.State = ConnectionState.Open) Then
            MyConnection.Close()
        End If