关于模糊查询,向textbox中添加已选择的listbox项目

[zhaojinsheng]

比如要在textbox中输入语句select 姓名 from 资料表
1.模糊匹配,当输入"s"时,listbox跳出"select","set"等供选择,现已解决

2.如何将这个模糊匹配且添加功能在textbox中的任何位置实现??
Private Sub ListBox1_MouseDoubleClick(ByVal sender As Object, ByVal e As System.EventArgs) Handles ListBox1.DoubleClick
If ListBox1.Items.Count < 1 Then
MessageBox.Show("项目为空！")
Else
Dim str As String = TextBox1.Text '将文本值赋给变量
Dim start As Integer = TextBox1.SelectionStart
Dim str1 As String() = Strings.Split(str, " ") '将字符串按空格分成不同数组
Dim str2 As String = str1(UBound(str1)) '取最后一个空格到光标的字符串然后搜索
Dim str3 As String = ListBox1.SelectedItem.ToString
TextBox1.Text = TextBox1.Text.Insert(start - Len(str2), str3)
TextBox1.Text = Replace(TextBox1.Text, str2, " ")
TextBox1.SelectionStart = start + Len(str3) - Len(str2)
' TextBox1.SelectionLength = 0
End If

End Sub)我的代码只能在textbox的1-3行,第四行开始就搜索不出内容了,不知道错在哪里?