掌握和使用TreeView加载数据

王朝other·作者佚名  2008-05-19
窄屏简体版  字體: |||超大  

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_vbdatabasereeview的节点添加1est.mdb"

End Sub

Private Sub Form_Unload(Cancel As Integer)

Set con = Nothing

End Sub

 
 
 
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