change textbox's value from pageload event, submit new values issue - asp.net

Question

I have created a form to update an access DB table. My issue is that when the text in the text boxes is changed and the form is submitted, the .text values stay the same as they were when the datareader loaded them on the page load event. How can I submit the values that the user updates, not what is already there from page load.
Code:
Public Property vehicleid As Integer
Public Property connstring As String = "myconnectionstring..."
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
vehicleid = Integer.Parse(Request.QueryString("vehicID"))
Dim svEnterdate, stocknum, make, model, color As String
Dim conn As New OleDbConnection(connstring)
Dim sql As String = "select * from vehicle where vehicleid=#vid"
Dim cmd As New OleDbCommand(sql, conn)
cmd.Parameters.AddWithValue("#vid", vehicleid)
conn.Open()
Dim dr As OleDbDataReader = cmd.ExecuteReader
While dr.Read
svEnterdate = dr("enterdate").ToString()
stocknum = dr("stock_num").ToString()
make = dr("make").ToString()
model = dr("model").ToString()
color = dr("color").ToString()
End While
conn.Close()
EnterDateTXT.Text = svEnterdate
StockNumTXT.Text = stocknum
MakeTxt.Text = make
ModelTXT.Text = model
ColorTxt.Text = color
End Sub
'inbetween these 2 events the user can manipulate all the controls .text values, yet the
' .text values of the submitted controls below are the same as the ones filled by the
'datareader
Protected Sub SubmitBTN_Click(ByVal sender As Object, ByVal e As EventArgs) Handles SubmitBTN.Click
Dim conn As New OleDbConnection(connstring)
Dim sql As String = "UPDATE Vehicle" & _
" SET stock_num=#stock, make=#make, model=#model, color=#color, enterdate=#enter " & _
"WHERE vehicleid=#vid"
Dim cmd As New OleDbCommand(sql, conn)
cmd.Parameters.AddWithValue("#vid", vehicleid)
cmd.Parameters.AddWithValue("#stock", StockNumTXT.Text)
cmd.Parameters.AddWithValue("#make", MakeTxt.Text)
cmd.Parameters.AddWithValue("#model", ModelTXT.Text)
cmd.Parameters.AddWithValue("#color", ColorTxt.Text)
cmd.Parameters.AddWithValue("#enter", EnterDateTXT.Text)
conn.Open()
cmd.ExecuteNonQuery()
conn.Close()
End Sub

Answer 1

In your page load code, Check For Post back
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
' Write your code to read data from database here
End
End Sub
If you dont check for postback in your page load event, Everytime when you click the submit button, It is going to excute the code in your page load ( load the content again to the text box) first. So whatever you entered in the textbox will be overwritten by the content form the database and that will be saved back again to the database.
To undestand this. Put a breakpoint in your Page_load event code and another in your button click event code. Now enter some value in textbox and click the button and see whether your code block in pageload is executing or not.
Checking the Postback check in your page_load will fix the problem.
http://msdn.microsoft.com/en-us/library/system.web.ui.page.ispostback.aspx