QueryString in ASP.NET

This blog explains -
  • What is QueryString?
  • Why do we use QueryString?
  • How to pass the values through QueryString?
  • How to retrieve the values from QueryString?
 QueryString
  • Query string is one of the technique to send data from one webform to another through URL.
  • Query string consist of two parts (field and value), and each of pair separated by ampersand (&).
  • ?(Question Mark), indicates the beginning of a query string and it's value.
  • There is a limit on the Query string length. Hence, Query strings cannot be used to send very long data.
  • Query strings are visible to the user, hence should not be used to send sensitive information (Like Username, Password), unless encrypted.
  • To retrieve the query string value, use Request object's QueryString property.
Lets understand with an example: 
  • To create the project -
  • Go to Start -> then All Programs and click Microsoft Visual Studio 2010
  • Go to File -> New -> Project..., Visual C# , Web. Then select ASP.NET Empty Web Application.
  • Provide the project a name and specify the location. 
Next: Right-click on Solution Explorer and add a two web forms (user.aspx, Mas_Employee.aspx) to your project.
 
Send the Values using QueryString :
 
Design your user.aspx as in the following.
 
 
Copythe following code in your button click event to send multiple query string values (Name, DeptNmae) through URL from user.aspxpage to Mas_Employee.aspx.
  1. protected void btnSend_Click(object sender, EventArgs e)  
  2. {  
  3.    Response.Redirect("/Application /Mas_Employee.aspx?Name=" + txtName.Text + "&DeptName=" + txtDeptName.Text);  
  4. }  
 Retrieve the values from QueryString:
 
Design your Mas_Employee.aspx as in the following
 
 
To retrieve the QueryString Values (Name, DeptNmae) in Mas_Employee.aspx copy the following code in your Mas_Employee.aspx.cs.
  1. protected void Page_Load(object sender, EventArgs e)  
  2. {  
  3.    if (!IsPostBack)  
  4.    {  
  5.       if (Request.QueryString["Name"] != null && Request.QueryString["Name"] != string.Empty)  
  6.          lblName.Text = Request.QueryString["Name"];  
  7.   
  8.       if (Request.QueryString["DeptName"] != null && Request.QueryString["Name"] != string.Empty)  
  9.          lblDeptName.Text = Request.QueryString["DeptName"];  
  10.    }  
  11. }  
Run the application and Provide Name and DeptName values and then click on Send. At this point you will get the following result.
 
 
Output:
 
 
Conclusion

QueryString are used to pass the data (limited data through URL) from one page to another page . For example. If we want to send one page control values to another page you can use QueryString.
 
I hope you enjoyed it. Please provide your valuable suggestions and feedback if you found this blog helpful.