how to use the primary key exeception in exceptional handling?

2 posts / 0 new

Last post

Tue, 05/25/2010 - 22:15

#1

surendarj

Offline

Joined: 05/23/2010

how to use the primary key exeception in exceptional handling?

i have one registration form which consists of username, password, confirmpassword and Register button.
When i will be typing the username, it should show whether the username is available or not. and i have changed the username column as primary key in sql database.

and also coding for primary key exception using exceptional handling.

so i need the coding for that requirement...

and also how to clear the text from the form...
thanks in advance..
please help me soon

please send the code to my email id: surendar_julakanti@yahoo.co.in

Sat, 05/29/2010 - 11:27

#2

admin

admin's picture

Offline

Joined: 11/14/2008

re: primary key exeception in exceptional handling

Use the following function to determine if the record exist on your table.

Public Function CountRows(ByVal sSQL As String)
        Dim CN As SqlConnection
        CN= New SqlConnection
 
        With CN
            If .State = ConnectionState.Open Then .Close()
 
            .ConnectionString = cnString
            .Open()
        End With
 
        Dim cmdCount As SqlCommand = New SqlCommand(sSQL, CN)
 
        CountRows = cmdCount.ExecuteScalar()
End Function

Call it using this code:

                Dim sSQL As String = "SELECT Count(*) FROM Users WHERE Username = '" & txtUsername.text & "'"
 
                Dim RecordCount As Integer = CountRows(sSQL)
 
                If RecordCount = 0 Then
                    MsgBox("Username already exists.", vbInformation)
 
                    Exit Sub
                End If

Pages

Add new comment