Query String
The most common approach to pass information to server is by using a query string in the URL. This approach is mostly found in search engines. For example, if you perform a search on the Google website, you’ll be redirected to a new URL that make use of your search parameters. For example:
http://www.google.com/search?q=shahu+college
The query string is the portion of the URL after the question mark. In example above, it defines a single variable named q, which contains the string shahu+college.
The advantage of the query string is that it’s lightweight and doesn’t apply any kind of burden on the server.
However, it has limitation also:
Information is limited to simple strings, which must contain URL-legal characters.
Information is clearly visible to the user and to anyone else who cares to eavesdrop on the Internet.
Many browsers impose a limit on the length of a URL (usually from 1 KB to 2 KB), you can’t place a large amount of information in the query string and still be assured of compatibility with most browsers.
The Response.Redirect() methodis used to build query string:
Response.Redirect("newpage.aspx?recordID=10");
You can send multiple parameters separated with an ampersand (&):
Response.Redirect("newpage.aspx?recordID=10&class=BCATY");
The receiving page has an easier time working with the query string. It can receive the values from the QueryString dictionary collection exposed by the built-in Request object:
string ID = Request.QueryString["recordID"];
classname = Request.QueryString["class"];
Cookies
Cookies provide a way to store information for later use. Cookies are small files that are created in the web browser’s memory (if they’re temporary) or on the client’s hard drive (if they’re permanent). One advantage of cookies is that they work transparently, without the user being aware that information needs to be stored.
As cookies are stored on the user’s computer as plaintext, you should never use them to store any sensitive data, such as a password.
The following line of code is used to create cookies:
HttpCookie myCookie = new HttpCookie("CookieName");
myCookie.Expires = DateTime.Now.AddMonths(3);
myCookie.Value = "My Cookie";
Response.Cookies.Add(myCookie);
To read cookie the line of code can be implemented as
HttpCookie myCookie = Request.Cookies.Get("CookieName");
if (myCookie != null)
{
Label1.Text = myCookie.Value; // would display "Cookie value"
}
Database Connectivity:
Inserting a record in the table:
Design of Application:
Programme code for the design:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h1>Student Information</h1><br />
Student P.R.No : <asp:TextBox ID=txtprno runat="server"></asp:TextBox><br />
Student Name : <asp:TextBox ID=txtsname runat="server"></asp:TextBox><br />
contact No : <asp:TextBox ID = txtcno runat="server"></asp:TextBox><br />
<asp:Button ID="btnSave" Text="Save" runat="server" onclick="btnSave_Click" />
<asp:Button ID="btnClear" Text="Clear" runat="server" />
<br />
<asp:Label ID="Label1" runat="server" Text=""></asp:Label>
</div>
</form>
</body>
</html>
C# code for database connectivity:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.OleDb;
using System.Data;
public partial class _Default : System.Web.UI.Page
{
OleDbConnection con = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=E:\DataBaseDemo\student.accdb");
OleDbCommand cmd;
protected void Page_Load(object sender, EventArgs e)
{
con.Open();
}
protected void btnSave_Click(object sender, EventArgs e)
{
string s;
s = "insert into studdtl values(" + txtprno.Text + ",'" + txtsname.Text + "'," + txtcno.Text + ")";
cmd = new OleDbCommand();
cmd.Connection = con;
cmd.CommandText = s;
cmd.ExecuteNonQuery();
Label1.Text = "Record Saved..." + txtprno.Text;
}
}
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