Primary Key error in ASP.NET

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Hi! Thank you very much for your nice tutorials on SQL Server at codeproject. Please, I need some help. I'm new in programming with ASP.NET in Microsoft Visual Studio 2008, with the page language being C#.

I made a simple application to register wireless connection users. When a user doesn't instert a primar key, in my case a MAC address, the following error msg is displayed: Violation of PRIMARY KEY constraint 'aaaaaclients_PK'. Cannot insert duplicate key in object 'dbo.clients'. The duplicate key value is (XXXXXXXXX).
The statement has been terminated.

I know why the message is displayed, but I want to customize this and put my own message as the user will not understand what that is. Please help me how to handle this.

The code (part) of the .aspx page for registering clients(where the error occurs) is this:

C#

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:wirelessConnectionString1 %>" InsertCommand="INSERT INTO [clients] ([FirstName], [Surname], [RegNo], [Brand], [MAC], [RegDate], [Expiry], [Remarks]) VALUES (@FirstName,@MAC)" 

ProviderName="<%$ ConnectionStrings:wirelessConnectionString1.ProviderName %>" 
SelectCommand="SELECT [FirstName], [Surname], [MAC] FROM [clients]" 

UpdateCommand="UPDATE [clients] SET [FirstName] = @FirstName, [Surname] = @Surname, WHERE [MAC] = @MAC">

<deleteparameters>
 
<asp:Parameter Name="MAC" Type="String" />

</deleteparameters>
<insertparameters> 

<asp:Parameter Name="FirstName" Type="String" />
 <asp:Parameter Name="Surname" Type="String" />
<asp:Parameter Name="MAC" Type="String" />


</insertparameters>

Thanks in Advance,

Frank.

Posted 7-Nov-11 2:17am

savedlema

Updated 7-Nov-11 2:19am

jim lahey

v2

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jim lahey · Answer 1 · 2011-11-07T02:31:00

You can handle the SqlDataSource.Inserting event:

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.sqldatasource.inserting.aspx[^]

You can use this event to check if the MAC parameter is a null or empty string and handle the situation accordingly before you even go near the database:

C#

private void On_Inserting(Object sender, SqlDataSourceCommandEventArgs e) 
{
    var pkValue = e.Command.Parameters["@MAC"].Value;

    if(string.IsNullOrEmpty(pkValue))
    {
        //Show some error message here assuming you've got a Label lblError in your page:
        lblError.Text = "You must specify a MAC Address";        

        //cancels the insert
        e.Cancel = true;
    }
}

shashikanth 2011 · Answer 2 · 2011-11-07T02:38:00

As we can Handle Application level and session level errors in Global asax page..
and page level errors..
you can use any one of that events..
to display your own Error messege, if you forget to catch any Exceptions

HTML

Server.GetLastError();
//Will retreives the latest Exception that was unhandled

And you can use this in Application error handler

C#

void Application_Error(object sender, EventArgs e)
       {
           // Code that runs when an unhandled error occurs
       }

RaisKazi · Answer 3 · 2011-11-07T02:41:00

Solution 4

You may use SqlDataSource.Updating Event to handle this error.

SqlDataSource.Updating Event

Write a Try-Catch Block in above Event to display your User-Friendly Error Message.

http://msdn.microsoft.com/en-us/library/0yd65esw(v=VS.100).aspx

Posted 7-Nov-11 2:41am

RaisKazi

Comments

thatraja 7-Nov-11 11:01am

Right, 5!

RaisKazi 7-Nov-11 11:24am

yup, Thanks. :)

thatraja · Answer 4 · 2011-11-07T02:28:00

Solution 1

You need to customize the things in your code.

Creating and Throwing Exceptions (C# Programming Guide)[^]
SqlException Class[^]
And an article in CP
Exception Handling in 3-Tier Architecture[^]

Posted 7-Nov-11 2:28am

thatraja

Comments

savedlema 9-Nov-11 12:19pm

Thank you. I'm following your links just now..

savedlema 9-Nov-11 14:14pm

friends,Some more help please.