.NET Tutorials, Forums, Interview Questions And Answers
Welcome :Guest
Sign In
Win Surprise Gifts!!!

Top 5 Contributors of the Month
Gaurav Pal
Post New Web Links

How to load dropdown with Null value?

Posted By:      Posted Date: September 27, 2010    Points: 0   Category :ASP.Net


For insertion, I have dropdown inside a form.

The dropdown is linked with sqldatasource which is retreiving distinct records from table.

In table there is no NULL value.

What I want to do that when user will access Insert page to insert record then like all textboxes, dropdown should also load with NULL value.

Any swift idea would be appreciated please.


View Complete Post

More Related Resource Links

Dropdown menu - Null or empty string??


I have drop dowm menu as follow.

<asp:ListItem Value="">none</asp:ListItem>
<asp:ListItem Value="STO">Stock</asp:ListItem>
<asp:ListItem Value="ORD">Order</asp:ListItem>

If I chose none, it stores data as "Null"

If I Query the data as below, I don't get the data has value of "Null"

SELECT tabale From type Where type <> STO or type <> ORD

I get data that has empty string but not Null.

Here is my question.

1, How do I write dropdown menu value in oder to get empty string instead of Null?
I did <asp:ListItem Value="">none</asp:ListItem> but this stores Null.

2, Why this Query won't pick up Null?
SELECT mytabale FROM type WHERE type <> STO or type <> ORD

Thank you for your help.

Could not load file or assembly 'Compliance, Version=, Culture=neutral, PublicKeyToken=null'

We recently upgraded from .NET 1.1 to .NET 3.5. The project was running fine until yesterday when I tried to create a set up project. When I add a new Websetup project and rebuild solution I get error :  Error 79 Could not load file or assembly 'Compliance, Version=, Culture=neutral, PublicKeyToken=null' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417) Y:\Development_Sites\Development_Server_RW\QMComet\SGEN Compliance Now when I run the project  , I get : Server Error in '/QMComet' Application. Parser Error Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately. Parser Error Message: Could not load type 'Jennison.Compliance.Global'.Source Error: Line 1: <%@ Application Codebehind="Global.asax.cs" Inherits="Jennison.Compliance.Global" %> Source File: /QMComet/global.asax    Line: 1     Please help. I wwas able to run the project before I tried to create a set up.   Thanks,Rohit

how to call dropdown SelectedIndexChanged event in page load event in c#


Hi everyone,

in my web form i have a department dropdown box, in its selectedIndexChanged event i have to fill the equipment dropdown box and in equiment dropdown selectedIndexChanged i have to fill out the other textboxs.

the depratment dropdown box get its value from sqldatasource.

 <asp:DropDownList ID="dp_deptname" runat="server" DataSourceID="SqlDataSource1" DataTe

Dropdown list in ASP.NET - How to get value selected

am sure this must be very simple, but unforunately I can't figure it out.
I have the following code which populates the dropdown lists from the database. This works fine. Now, when the user selects a particular employee name from the list, I want to get the Employee Id of the selected employee. i.e. I need to get the "Eid" value. I can do this if the EId is loaded in the dropdown list, but in this case only the employee name is displayed. Please let me know howI can get the Eid value even though it is not loaded in the dropdown list.
I would really appreciate your help

Editable Gridview with Textbox, CheckBox, Radio Button and DropDown List

This is an example of an editable gridview containing different ASP.NET controls. When user wants to edit values in gridview, she/he can use these controls to edit existing values in Gridview Edit Mode.

Using the Code

Combine, minify and compress JavaScript files to load ASP.NET pages faster

Websites are getting more interactive these days and most of this interactivity comes from JavaScript. People are using different JavaScript libraries and frameworks to make their websites more interactive and user friendly.

DataTable - Load from IDataReader - CreateDataReader - ReadXml WriteXml - Free ADO.NET Tutorials

The DataTable in ADO.NET 2.0 has been seriously beefed up and I absolutely love it. Not everything we consume deals with multiple resultsets and requires the ever popular DataSet. With the cool new features in the ADO.NET 2.0 DataTable, we can get many of the cool features in the DataSet without all the extra baggage and memory footprint particular to multiple resultsets.

Load DataTable from IDataReader

ActiveSync 4.5 (Free Down Load) using in Windows Mobile Pocket Pc

Microsoft ActiveSync 4.5 is the latest sync software release for Windows Mobile-powered devices. ActiveSync provides a great synchronization experience with Windows®-powered PCs and Microsoft Outlook right out of the box.


* Faster file transfer speed and photo sync via Outlook are only available for Windows Mobile 5.0 powered devices.
* Remote PC Sync (via WiFi or LAN) has been removed due to Enterprise customer feedback around security issues.
* Customers using Microsoft Exchange 2003 Service Pack 2 with devices running the Messaging and Security Feature Pack for Windows Mobile 5.0 will benefit from the following feature enhancements included in ActiveSync 4.5: Direct Push Technology, local device wipe, and certificate powered authentication to Microsoft Exchange.
* Microsoft® Outlook® 2000 is not supported by ActiveSync 4.5. It is highly recommended that users upgrade to Microsoft® Outlook® 2003 messaging and collaboration client.
* Conversion of database files for use on a mobile device is not supported by ActiveSync 4.5. On previous versions, this feature was limited to devices running Windows Mobile software for Pocket PC 2003 and earlier.
* Conversion of font files for use on a mobile device is not supported by ActiveSync 4.5. On previous versions, this feature was limited to devices running Windows Mobile software for Pocket P

Binding an array to dropdown list


I have the following string which is a list of urls. How do I get this to work so the url shows for the selection and also is the value?      


allLinks = newAllLinks
        Me.DropDownList1.DataTextField = "Link"
        Me.DropDownList1.DataValueField = "LinkURL"
        Me.DropDownList1.Items.Insert(0, New ListItem(" - Select - ", 0))
        Me.DropDownList1.DataSource = allLinks


 ArgumentNullException: Value cannot be null.
Parameter name: container]
   System.Web.UI.DataBinder.GetPropertyValue(Object container, String propName) +121
   System.Web.UI.DataBinder.GetPropertyValue(Object container, String propName, String format) +8

website load testing


How can i check "load testing" on my site (its using vb.net and SQL server)? Any free tool available or can it be done through windows server IIS?

Gridview with a dropdown list for editing


Hello. I am working through Scott Mitchell's ASP.Net in 24 hours book. I am finishing the photo album project.

I have a GridView that retrieves a list of uploaded photo rows for the logged-in user.
The GridView is for editing and deleting rows.

The photo Category field in the Gridview is a dropdown list. The text entry field was deleted after converting this field to a Template.

Like the uploaded photos, these Categories are user-specific. They are created in another web page.

Users also have the option to select "none" for the category when they upload an image.

For the GridView:  The Category ID field's ItemTemplate and EditItemTemplate both have a " - None - " choice added to them.

I am getting this error:

'pictureReadOnlyCategories' has a SelectedValue which is invalid because it does not exist in the list of items. Parameter name: value


Note: The ID for the ItemTemplate for that dropdown list is the ID listed above in the error: "pictureReadOnlyCategories".


Am I missing some step in this process of changing a GridViews text field to a dropdown that can be used for editing? I went through the book's instructions three times.

Here is my code for the dropdown list and a screenshot of the Design

Dropdown Event (Template Field)



I have grid view control that includes a dropdown control in a template field.

I wish to execute some code when the value is changed in the dropdown list.  Can't figure out how to capture this event though?

Any suggestions?

Open ModalPopup dialog on page load


Is there a way to make a modal popup panel active on page load so that the user can't do anything until they deal with the popup dialog?

JQuery Treeview plugin is not working with Ajax page load in ie8


Hi there,

I developed a page where i m using jquery treeview plugin to generate tree. It worked fine on FF, IE8 with out ajax.

But when my page loads thro' ajax call in IE8, it is not collapsing or expanding tree.

Any idea?

Thanks in advance.

How to check for null/empty strings on dynamic objects?


What is the proper way to check for null or empty strings on dynamic objects? This is the only solution I've found so far:

if (admin.PasswordHash.GetType() == typeof(DBNull) || admin.PasswordHash == string.Empty)

If the field is null, the object returned is DBNull.Value, but if the field is empty string, it's return as a System.String object. This makes it impossible to do regular "admin.PasswordHash == DBNull.Value" check, as that will fail whenever the field has been set to empty string. Is my example the right (and only) way to go?

Populating Dropdown List using FK


Hi Folks,

2 Questions. I am trying out Data Entities in VWD 2010 Express. I have a parent (Customers) and child (Orders) table. Customers table has FirstName, LastName and Email columns.

Q1. When I view/edit/insert an Order, it shows the customer's first name in dropdown list whereas I want the full name. How can this be done?

Q2. How can I change the default behavior of PK/FK relationship so that customer's Email is displayed instead of Name?

Any help will be much appreciated.


Users getting logged out because HttpContext.Current is null


We've  been trying to fix this one for a couple years, and I'm just out of ideas, so any help is really appreciated!

We've got a fairly large, complex web application that uses Forms Authentication to authenticate users.  Throughout the application we store and retrieve information about users in the Session object, and in some cases in cookies.  In a couple places we check for the existence of the context, and if it's null we send the user back to the login page to re-establish the session. 

Just a quick run-down of this web app: C#, .NET 3.5, IIS 6, ASP.NET State Service to manage session

As for the session timer, we use our own home-grown timer, which is basically a client-side timer, which is backed up by a check to the SQL database to see when their last activity was.  This seems to work well for us.  It's not perfect, but it allows us to notify the user before the session times out, and allows us to be certain we're not logging a user out before their 60 minutes of inactivity is up.

What's happening is that certain users are being logged out after just a few minutes.  We've eliminated the timer as a cause and believe what's happening is the HttpContext.Current is null, so the user is logged out.  We do not know why the HttpContext.Current is null, and I underst

ASP.NetWindows Application  .NET Framework  C#  VB.Net  ADO.Net  
Sql Server  SharePoint  Silverlight  Others  All   

Hall of Fame    Twitter   Terms of Service    Privacy Policy    Contact Us    Archives   Tell A Friend