数据库查询问题

第一个问题：这个查询代码是按排序方法查找的，能不能输入头一个字母就查找出结果的代码？
比如"D*'就把D开头的所有记录

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
        Dim intposition As Integer
        Select Case ComboBox1.SelectedIndex
            Case 0
                objdataview.Sort = "姓名"
            Case 1
                objdataview.Sort = "地址"
            Case 2
                objdataview.Sort = "联系电话"
        End Select
        intposition = objdataview.Find(TextBox1.Text)
        If intposition = -1 Then
            txtrecordposition.Text = "找不到数据"
        Else
            objcurrencymanager.Position = intposition
        End If
        showposition()
    End Sub
第二个问题：查找记录中摸个列（数据类型）的最大值代码怎么写？