VB dot net session value set in text box not change - asp.net

Question

In one of my vb page i am setting the value of a textbox through the value coming from session. In the same page i want to perform an edit operation of the record. On the page load i displayed the variables in textboxes and after editing values when i submit and take the value from the textboxes, it still take the value i set through session. It do not take the value changed in the textbox rather it shows the value assigned at the time of page load. Please help.
Here is my code,
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.SessionState.HttpSessionState
Imports System.Drawing
Imports System.Drawing.Printing
Partial Class Default2
Inherits System.Web.UI.Page
Dim cn As New SqlConnection
Dim cmd As New SqlCommand
Dim dr As SqlDataReader
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
cn.Open()
Dim var As String
var = Session("S2").ToString()
TextBox1.Text = var
Session.Remove("S2")
cmd = New SqlCommand("select * from HouseDetails where OccupantName= '" & TextBox1.Text & "' ", cn)
dr = cmd.ExecuteReader
While (dr.Read)
Label1.Text = dr(1)
Label2.Text = dr(2)
Label3.Text = dr(3)
TextBox3.Text = dr(4)
DropDownList3.SelectedItem.Text = dr(5)
TextBox2.Text = dr(6)
TextBox4.Text = dr(7)
TextBox5.Text = dr(8)
DropDownList4.Text = dr(9)
End While
cn.Close()
End Sub
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
cn.Open()
Dim query As String = ("UPDATE HouseDetails SET OccupantName='" & TextBox1.Text & "' where HouseNum='" & Label3.Text & "'")
cmd = New SqlCommand(query, cn)
Dim x As Integer = cmd.ExecuteNonQuery()
cn.Close()
End Sub
Protected Sub TextBox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
End Sub
End Class

Answer 1

Add postback prevention with the line "If (Page.IsPostBack = false) Then", for not assigning the same value again to the textbox,
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.SessionState.HttpSessionState
Imports System.Drawing
Imports System.Drawing.Printing
Partial Class Default2
Inherits System.Web.UI.Page
Dim cn As New SqlConnection
Dim cmd As New SqlCommand
Dim dr As SqlDataReader
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If (Page.IsPostBack = false) Then
cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
cn.Open()
Dim var As String
var = Session("S2").ToString()
TextBox1.Text = var
Session.Remove("S2")
cmd = New SqlCommand("select * from HouseDetails where OccupantName= '" & TextBox1.Text & "' ", cn)
dr = cmd.ExecuteReader
While (dr.Read)
Label1.Text = dr(1)
Label2.Text = dr(2)
Label3.Text = dr(3)
TextBox3.Text = dr(4)
DropDownList3.SelectedItem.Text = dr(5)
TextBox2.Text = dr(6)
TextBox4.Text = dr(7)
TextBox5.Text = dr(8)
DropDownList4.Text = dr(9)
End While
cn.Close()
End If
End Sub
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
cn.Open()
Dim query As String = ("UPDATE HouseDetails SET OccupantName='" & TextBox1.Text & "' where HouseNum='" & Label3.Text & "'")
cmd = New SqlCommand(query, cn)
Dim x As Integer = cmd.ExecuteNonQuery()
cn.Close()
End Sub
Protected Sub TextBox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
End Sub
End Class

Answer 2

I fancy you're missing a check for IsPostBack to see whether or not this is a new request or a submission.
If (Not IsPostBack) Then
' populate for first load
End If

Answer 3

You have to put your code in IsPostback property.
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.SessionState.HttpSessionState
Imports System.Drawing
Imports System.Drawing.Printing
Partial Class Default2
Inherits System.Web.UI.Page
Dim cn As New SqlConnection
Dim cmd As New SqlCommand
Dim dr As SqlDataReader
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If (!IsPostBack) Then
cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
cn.Open()
Dim var As String
var = Session("S2").ToString()
TextBox1.Text = var
Session.Remove("S2")
cmd = New SqlCommand("select * from HouseDetails where OccupantName= '" & TextBox1.Text & "' ", cn)
dr = cmd.ExecuteReader
While (dr.Read)
Label1.Text = dr(1)
Label2.Text = dr(2)
Label3.Text = dr(3)
TextBox3.Text = dr(4)
DropDownList3.SelectedItem.Text = dr(5)
TextBox2.Text = dr(6)
TextBox4.Text = dr(7)
TextBox5.Text = dr(8)
DropDownList4.Text = dr(9)
End While
cn.Close()
End If
End Sub
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
cn.Open()
Dim query As String = ("UPDATE HouseDetails SET OccupantName='" & TextBox1.Text & "' where HouseNum='" & Label3.Text & "'")
cmd = New SqlCommand(query, cn)
Dim x As Integer = cmd.ExecuteNonQuery()
cn.Close()
End Sub
Protected Sub TextBox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
End Sub
End Class