asp.net click DataGrid column Header sort (vb.net)

asp.net|datagrid| sorting please follow the steps:
Properties of 1:datagrid
Allowsorting= ' true ': Enable DataGrid sorting
2: Inside the HTML (added to the table) add a <input id= "SortField" type= "hidden" value= "activity_student_id" "Name=" SortField "runat=" Server >
Change fields as Sort by
Sort expression and Word fields in 3:datagrid consistent


4: Add namespace Imports System.Data
Imports System.Data.SqlClient

5:if InStr (SortField. Value, "desc") = 0 Then
SortField. Value = e.sortexpression & "desc"
Else
SortField. Value = e.sortexpression & "ASC"
End If
Bindgrid ()
Description: "1" e.sortexpression equals the name of the field named "Sorted link being pressed".
"2" If InStr (SortField. Value, "desc") = 0 if the original sort method was sorted by "ascending sort." The Sort method (Softfield.value) is then set to "Desc" (for descending sorting). Otherwise set to "", expressed as "ascending sort"
"3" At this time Softfield.value obtained is "field" + "sort" then Bindgrid ().
Sub Bindgrid ()
txtSQL = "SELECT * from .... ... where ...?..
Dbset = ExecuteSQL (txtsql, errormsg) ' The way every programmer gets a dataset is different,
' Anyway, you'll find a way to get a dataset dataset, you can also refer to my VB Connection sqlserver2000 database function
Dim dtable as DataTable = dbset.tables (0)
Dim Dview as New DataView (dtable)
Dg. Sort = SortField. Value
Dg. DataSource = Dview
Dg. DataBind ()
End Sub