Query String , ViewState , Session

Query String : to send information through URL

 Response.Redirect("Default3.aspx?val1=ass&val2=" & TextBox1.Text)

The query string cannot be viewed as well as the current page URL will be shown even after the redirection of web page.

        Server.Transfer("Default3.aspx?val1=ass&val2=" & TextBox1.Text)


To retrieve information from URL
 Response.Write(Request.QueryString("val1") + "  " + Request.QueryString("val2"))



Viewstate : syntax

 increment of  viewstate  value which can be saved even after the page postback.
           ViewState("cnt") = ViewState("cnt") + 1 


Session : syntax


' Check in Page load of  a webpage

if  textbox1.text= "vamsi" then
Session("username")=textbox1.text 
response.redirect("homepage.aspx")
endif

'below code with in homepage.aspx  at pageload even


Response.write("Welcome " + Session("username"))


'Checking of user name on each webpage at pageload event

'the below code should check whether the username is hari or not. if its hari its move on to the else part or it will redirect the page which created by the user "errpage.aspx" 

' the thing is it may not allow the current page to the unauthorised user

If Session("username") <> "hari" Then

            Response.Redirect("errpage.aspx")


        Else

            Response.Write(Request.QueryString("val1") + "  " + Request.QueryString("val2"))

        End If