TreeView控件在编制程序过程中用得比较多。正确的掌握和使用这个控件，可以很好的表示层次关系的数据。在数据库应用系统中，我们可以用TreeView来显示树形结构，如显示目录树、显示班级信息等等，有着很重要的作用

看看下面一个实际的问题：每个年度都有许多的班级，将这些数据层次表示

数据库:access

表:Test

字段:bh(班级编号,文本，主键),nj(年级,文本)

功能：以层次关系表现出数据

测试数据：

添加TreeView控件，2个按钮

2个按钮分别用了两种方法显示数据。但是第二种方法明显优于第一种。

可以仔细的看代码


'引用microsoft activex data object 2.x library

Dim nddata As Node

Dim cnn As ADODB.Connection

Dim rs1 As New ADODB.Recordset

Dim rs2 As New ADODB.Recordset


Private Sub Command1_Click()

On Error Resume Next

Set nddata = TreeView1.Nodes.Add(, , "db", "班级信息")

nddata.Expanded = True

Dim intcount As Integer

Dim inttable As Integer

Dim intfield As Integer

Dim intfn As Integer


rs1.Open "select nj from test group by nj", cnn, 1, 3

inttable = rs1.RecordCount


Do While inttable <> intcount

Set nddata = TreeView1.Nodes.Add("db", tvwChild, "F" & rs1.Fields("nj"), rs1.Fields("nj"))

rs2.Open "select bh,nj from test where nj='" & rs1.Fields("nj") & "'", cnn, 1, 3

intfield = rs2.RecordCount

If intfield <> 0 Then

intfn = 0

Do While intfield <> intfn

Set nddata = TreeView1.Nodes.Add("F" & rs1.Fields("nj"), tvwChild, "S" & rs2.Fields("bh"), rs2.Fields("bh"))

rs2.MoveNext

intfn = intfn + 1

Loop

End If

rs2.Close

rs1.MoveNext

intcount = intcount + 1

Loop

rs1.Close

End Sub


‘第二种方法

Private Sub Command2_Click()

On Error Resume Next

Set nddata = TreeView1.Nodes.Add(, , "db", "班级信息")

nddata.Expanded = True

rs1.Open "select * from test", cnn, 1, 3


Do While Not rs1.EOF

If ca <> rs1.Fields("nj") Then

Set nddata = TreeView1.Nodes.Add("db", tvwChild, "F" & rs1.Fields("nj"), rs1.Fields("nj"))

ca = rs1.Fields("bb")

End If


Set nddata = TreeView1.Nodes.Add("F" & rs1.Fields("nj"), tvwChild, "S" & rs1.Fields("bh"), rs1.Fields("bh"))

rs1.MoveNext

Loop

rs1.Close

End Sub


Private Sub Form_Load()

Set cnn = New ADODB.Connection

cnn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=F:\csdn_vb\database\treeview的节点添加\1\test.mdb"


End Sub


Private Sub Form_Unload(Cancel As Integer)

Set con = Nothing

End Sub