使用递归从数据库读取数据来动态创建菜单

Private m As New MainMenu()

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Dim conn As New SqlConnection("server=localhost;uid=sa;pwd=;database=jiang")

        Dim cmd As New SqlCommand("select * from a_menu ", conn)

        Dim ds As New DataSet()

        Dim sqldpr As New SqlDataAdapter(cmd)

        sqldpr.Fill(ds, "menu")

        Me.DataGrid1.DataSource = ds.Tables("menu")

        '创建关系

        Dim dr As New DataRelation("self_menu", ds.Tables("menu").Columns("MenBh"), ds.Tables("menu").Columns("Bhparent"))

        ds.Relations.Add(dr)

        Dim r1 As DataRow

        '查找最高的菜单级别,也就是Bhparent列为空的行

        For Each r1 In ds.Tables("menu").Rows

            If r1.IsNull("Bhparent") Then

                addmenuitem(r1, Nothing)

            End If

        Next

        Me.Menu = m '指定主窗体菜单

    End Sub

    '递归函数

    Private Sub addmenuitem(ByVal r As DataRow, ByVal item As MenuItem)

        Dim mi As MenuItem

        '如果是最外层菜单，要直接添加

        If item Is Nothing Then

            mi = m.MenuItems.Add(r.Item("MenText"))

        Else '如果是下级菜单要在菜单项的上级添加

            mi = item.MenuItems.Add(r.Item("MenText"))

        End If

        Dim r2 As DataRow

        For Each r2 In r.GetChildRows("self_menu")

            addmenuitem(r2, mi)

        Next

    End Sub

'--------------------------------------------------------一种方法的改进