error in connection for login form any help with the attached code

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  10 years ago

  by edriso

  hassan edris

  andover, United Kingdom

  Joined 10 years ago

  hi, i am new in vb.net in the login form if i enter an invalid username the next time it gives me this error "Not allowed to change the 'ConnectionString' property. The connection's current state is open."

  any help with the following code

  Imports System.Data Imports System.Data.OleDb Public Class LoginForm1 Dim DbCon As New OleDb.OleDbConnection Dim dbUp As New OleDb.OleDbCommand Dim Read As OleDb.OleDbDataReader

  Private Sub OK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OK.Click
  
      DbCon.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\login.mdb"
      DbCon.Open()
      dbUp.Connection = DbCon
      dbUp.CommandType = CommandType.Text
      dbUp.CommandText = "Select * from LOGIN where Username= '" & UsernameTextBox.Text & "' and Password= '" & PasswordTextBox.Text & "'"
      dbUp.Parameters.Add("Username", Data.OleDb.OleDbType.Variant)
      dbUp.Parameters.Add("Password", Data.OleDb.OleDbType.Variant)
      dbUp.Parameters("Username").Value = UsernameTextBox.Text
      dbUp.Parameters("Password").Value = PasswordTextBox.Text
      Read = dbUp.ExecuteReader
      With Read
          If .Read Then
              Me.Hide()
              Form1.Show()
          Else
              UsernameTextBox.Clear()
              PasswordTextBox.Clear()
              MessageBox.Show("Invalid Username or Password")
              UsernameTextBox.Focus()
          End If
  
  
      End With
  
  End Sub
  

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• • Reply

  10 years ago

  by jhpajiri

  JasJer JashJer

  Riyadh, Saudi Arabia

  Joined 10 years ago

  Try this source code of mind:

  Dim strQuery As String Dim cmd As OleDbCommand

  Dim sda As OleDbDataReader
  Dim con As OleDbConnection
  

  con = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\My Files\Inventory\database\dbInventory.mdb;Persist Security Info=True;") con.Open()

  strQuery = "SELECT *FROM qryUsers_Group WHERE UserName='" & txtUserName.Text.Trim() & "' AND Password='" & FuncCls.EncryptPassword(txtPassword.Text.Trim()) & "'"

          cmd = New OleDbCommand(strQuery, con)
          sda = cmd.ExecuteReader
          If sda.Read() Then
              lblMessage.Text = "Password Successful."
  

  Else lblMessage.Text = "Invalid Password." End If

          sda.Close()
  

  if you want SQL i can give you, or even stored Procedure.

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