Query to find non unique column from a table

I have a users table that has over 10,000 registered users (from a database that I've inherited). The original code allows for multiple registrations with the same email address which I want to eliminate. 

asp:XXXXX is not a known element. This can occur if there is a compilation error in the web site.

Problem occurred when I re-install Visual Stdio 2005...after digging for awhile i find the solution. Changing tag prefix did the job.
<webconfig

<pages>

<controls>

<add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>

</controls>

</pages>

change tagPrefix="asp" to tagPrefix="ajax" or whatever prefix you want. Then change your existing ajax control tags to use that prefix instead. E.g. <asp:UpdatePanel...> becomes <ajax:UpdatePanel...>

Database Connectivity Class(layered)

This is a custom Class, Tested and error free. Download it and copy and paste in your solution within Appcode folder. and call the methods via its class name .
here is the Download link: Download
hope this will help you.

Editable Dropdownlist using java script

Introduction

In ASP.Net Dropdownlist control cannot be editable by default. We can easily overcome this problem. This article is used to overcome this issue.

Using the code

Create one blank asp.net web page(Default.aspx) and include one textbox and dropdownlist control. see the following code.

<asp:TextBox ID="txtDisplay" runat="server"></asp:TextBox>

<asp:DropDownList ID="ddSelect" runat="server">

    <asp:ListItem Value="test1" >test1</asp:ListItem>

    <asp:ListItem Value="test2">test2</asp:ListItem>

</asp:DropDownList>

       

After inserted this controls into web page we need to set the following style into textbox control.

style="position:absolute" 

The position property places an element in a static, relative, absolute or fixed position. There are four types of position like static, relative, absolute and fixed.

Value	Description
static	Default. An element with position: static always has the position the normal flow of the page gives it (a static element ignores any top, bottom, left, or right declarations)
relative	An element with position: relative moves an element relative to its normal position, so "left:20" adds 20 pixels to the element's LEFT position
absolute	An element with position: absolute is positioned at the specified coordinates relative to its containing block. The element's position is specified with the "left", "top", "right", and "bottom" properties
fixed	An element with position: fixed is positioned at the specified coordinates relative to the browser window. The element's position is specified with the "left", "top", "right", and "bottom" properties. The element remains at that position regardless of scrolling. Works in IE7 (strict mode)

<asp:TextBox style="position:absolute" ID="txtDisplay" runat="server"></asp:TextBox> 

After adding the position style we need to set the equal width for both textbox and dropdownlist control.

<asp:TextBox style="width:120px;position:absolute" ID="txtDisplay" runat="server"></asp:TextBox>

<asp:DropDownList ID="ddSelect" style="width:140px" runat="server">

<asp:ListItem Value="test1" >test1</asp:ListItem>

<asp:ListItem Value="test2">test2</asp:ListItem>

</asp:DropDownList>

After adding the Styles we need to create javascript function. This function is used to display the selected dropdwon

text into textbox control.

<script language="javascript" type="text/javascript">

function DisplayText()

{

    document.getElementById("txtDisplay").value = document.getElementById("ddSelect").value;

    document.getElementById("txtDisplay").focus();

}

</script>

After adding the javascript function. use this function for Dropdown change event fires.

Add the following code into Default.aspx.cs file.

protected void Page_Load(object sender, EventArgs e)

{

         ddSelect.Attributes.Add("onChange", "DisplayText();");

}

Submit form on Enter Key Default submit Button

Whenever we want user to submit a form by filing out some textboxes on the aspx page, though we provide the button to submit the form but user prefer to press enter and expect the form to be submitted