Simple Explanation for very beginners of Query String

Query String allows you to pass values between the asp.net pages.

Query String allows you to pass values between the asp.net pages.

Let us say, you are navigating to below URL



In above URL, you are navigating to a page called Add.aspx and Number1 and Number2 are query string to page Add.aspx.

To create Query String,

1. Add a question mark (?) to URL.
2. After Question mark, give variable name and value separated by equal to (=).
3. If more than one parameter need to be passed then separate them by ampersand (&).

To read query String,
Say your URL is,
http://localhost:12165/Add.aspx?Number1=72&Number2=27

Then to read query string, on Add.aspx



You can read by passing exact variable name in index or,



You can read, by passing index value as above.

Now, I am going to show you a very basic sample,

1. I will create a page with two text boxes and one link button.
2. I will pass text boxes values as query string to other page on click event of link button.
3. On the other page, I will read the query string value and will add them in display in a label.

I have created a new asp.net application. Then I dragged and dropped two textboxes and one link button on the page. On click event of link button, I am performing the below operation.



I am constructing the URL, as to navigate to Add.aspx page and then appending two query strings from textbox1 text and textbox2 text.

Now, add a page to project say Add.aspx . Drag and drop a label on the page. On the page load event perform the below operation.



So, when you run the application you will get the output as below,




For your reference, the whole source code is given below,

Default.aspx.cs

using System;
usingSystem.Collections.Generic;
usingSystem.Linq;
usingSystem.Web;
usingSystem.Web.UI;
usingSystem.Web.UI.WebControls;

namespacequeryparameterexample
{
publicpartialclass_Default : System.Web.UI.Page
    {
protectedvoidPage_Load(object sender, EventArgs e)
        {
 
        }

protectedvoid LinkButton1_Click(object sender, EventArgs e)
        {
stringurltoNaviget = "~/Add.aspx?Number1=" +
                                     TextBox1.Text +
"&Number2=" +
                                     TextBox2.Text;
 
            LinkButton1.PostBackUrl = urltoNaviget;
        }
    }
}

Add.aspx.cs

using System;
usingSystem.Collections.Generic;
usingSystem.Linq;
usingSystem.Web;
usingSystem.Web.UI;
usingSystem.Web.UI.WebControls;

namespacequeryparameterexample
{
publicpartialclassWebForm1 : System.Web.UI.Page
    {
protectedvoidPage_Load(object sender, EventArgs e)
        {

string number1 = Request.QueryString[0];
string number2 = Request.QueryString[1];

// The other way to Read the values
//string number1 = Request.QueryString["Number1"];
//string number2 = Request.QueryString["Number2"];

int result = Convert.ToInt32(number1) + Convert.ToInt32(number2);
            Label2.Text = result.ToString();
 
        }
    }
}

I hope this post is useful. Thanks for reading. Happy Coding.