how to check the username is already exists in table...!

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  12 years ago

  by doteco

  Doug Coates

  , Australia

  Joined 12 years ago

   hi every one...!

  em creating a create user account page.

  i want to check the username is already exists in my database table or not?

  if exists then give me a error message that username is already exists if not then account will be successfully create.

   
  my code is:

  <script language="VB" runat="server">
     Dim objConnection As OleDbConnection
     Sub Page_Load(Source As Object, E As EventArgs)
             objConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; " _
          & "DATA SOURCE=" _
              & Server.MapPath("nwind.mdb;"))
     End Sub
  
     Sub btnInsert_Click(Sender As Object, E As EventArgs)
       If Page.IsValid Then
                 Dim strSQL As String = "INSERT INTO login (username, [password]) " & _
                            "VALUES (?, ?)"
  
  
         Dim dbComm As New OleDbCommand(strSQL, objConnection)
                 dbComm.Parameters.Add("UserName", OleDbType.VarChar, 32, "UserName")
                 dbComm.Parameters.Add("Password", OleDbType.VarChar, 128, "Password")
  
                 dbComm.Parameters("UserName").Value = txtUserName.Text
                 dbComm.Parameters("Password").Value = txtPassword.Text
  
         Try
           objConnection.Open()
           dbComm.ExecuteNonQuery()
         Catch ex As Exception
           Response.Write(ex.Message)
           Response.End()
         Finally
           If objConnection.State = ConnectionState.Open Then
             objConnection.Close()
           End If
         End Try
  
         Response.Write("A new record has been added")
         Response.End()
       End If
     End Sub
     </script>
   i will look forward for your positive response.

   

  Regards,

  Asad_Black 

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• • Reply

  12 years ago

  by mikefenej

  Mike Fenej

  , United States

  Joined 12 years ago

  Before Insert, Create an Query like this;

       Select count(*) From login where UserName like 'Parameter' [ ur parameter]...

  if the query returns more than 0 , then the user is avail else not...

   

  In case of Sql Server, Use if Exists( Select UserName from Login where UserName like '@Username')

  i.e in both cases before insert , pass the username parameter to ur query and check the count is having 0 or not....

  if 0 - new insert... else already exists

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• • Reply

  12 years ago

  by doteco

  Doug Coates

  , Australia

  Joined 12 years ago

   this is my code and it does not work.

  i dont know whatz de problem in this code.
   

   

   

  <script language="VB" runat="server">
     Dim objConnection As OleDbConnection
     Sub Page_Load(Source As Object, E As EventArgs)
             objConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; " _
          & "DATA SOURCE=" _
              & Server.MapPath("nwind.mdb;"))
         End Sub
        
        
        
  
         Sub btnInsert_Click(ByVal Sender As Object, ByVal E As EventArgs)
            
             Dim query As String
             query = "Select Count(*) From login Where username = ?"
             Dim result As Integer = 0
            
             If result > 0 Then
            
            
                
                 Dim strSQL As String = "INSERT INTO login (username, [password]) " & _
                            "VALUES (?, ?) "
  
                
                
                
  
                 Dim dbComm As New OleDbCommand(strSQL, objConnection)
                 dbComm.Parameters.Add("UserName", OleDbType.VarChar, 32, "UserName")
                 dbComm.Parameters.Add("Password", OleDbType.VarChar, 128, "Password")
  
                 dbComm.Parameters("UserName").Value = txtUserName.Text
                 dbComm.Parameters("Password").Value = txtPassword.Text
  
                 Try
                     objConnection.Open()
                     dbComm.ExecuteNonQuery()
                 Catch ex As Exception
                     Response.Write(ex.Message)
                     Response.End()
                 Finally
                     If objConnection.State = ConnectionState.Open Then
                         objConnection.Close()
                     End If
                 End Try
  
                 Response.Write("A new record has been added")
                 Response.End()
            
               
             Else
                 Response.Write("your username is already exist")
             End If
       
            
         End Sub
   
     </script>
  
  Dim objConnection As OleDbConnection Sub Page_Load(Source As Object, E As EventArgs) objConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; " _ & "DATA SOURCE=" _ & Server.MapPath("nwind.mdb;")) End Sub Sub btnInsert_Click(ByVal Sender As Object, ByVal E As EventArgs) Dim query As String query = "Select Count(*) From login Where username = ?" Dim result As Integer = 0 If result > 0 Then Dim strSQL As String = "INSERT INTO login (username, [password]) " & _ "VALUES (?, ?) " Dim dbComm As New OleDbCommand(strSQL, objConnection) dbComm.Parameters.Add("UserName", OleDbType.VarChar, 32, "UserName") dbComm.Parameters.Add("Password", OleDbType.VarChar, 128, "Password") dbComm.Parameters("UserName").Value = txtUserName.Text dbComm.Parameters("Password").Value = txtPassword.Text Try objConnection.Open() dbComm.ExecuteNonQuery() Catch ex As Exception Response.Write(ex.Message) Response.End() Finally If objConnection.State = ConnectionState.Open Then objConnection.Close() End If End Try Response.Write("A new record has been added") Response.End() Else Response.Write("your username is already exist") End If End Sub

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  11 years ago

  by as_dev

  Ameya Sawant

  Adelaide, Australia

  Joined 11 years ago

  Try openning the connection before assigning it to command object.

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