I need a little help with this.
I don't usually use a DataReader in this way but now have a need for a one way, forward communication this allows.

Anyway I got this code for the reader off the net but what it doesn't seem to handle is the null values in the db.
The repro is:
I do have a matching username and pcname but the user choose not to password protect, so the Password field is null.

Code:
Private Sub btnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLogin.Click

        If txtUsername.Text = "" Then
            MessageBox.Show("Please complete the required fields..", "Authentication Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
        Else

            ' Check if user exist in OneData database
            ' Connect to DB

            Dim conn As New System.Data.OleDb.OleDbConnection()
            conn.ConnectionString = My.Settings.OneDataConnectionString


            Try
                'Select the Staff record that matches the username, pcname and password
                Dim sql As String = "SELECT * FROM IDStaff WHERE StaffName= '" & Trim(txtUsername.Text) & "'" & _
                    " AND PCNAME= '" & Trim(txtPcName.Text) & "'" & " AND [Password] = '" & Trim(txtPassword.Text) & "'"

                Dim sqlCom As New System.Data.OleDb.OleDbCommand(sql)

                'Open Database Connection
                sqlCom.Connection = conn
                conn.Open()

                Dim sqlRead As System.Data.OleDb.OleDbDataReader = sqlCom.ExecuteReader()
              
                'Check if this user is in the database
                If sqlRead.Read() Then

                    'Yes, username/password/pcname check has passed
                    UserModule.PCName = txtPcName.Text
                    UserModule.UserName = txtUsername.Text

                    Me.Close()

                Else
                    ' No username/password/pcname checked failed
                    ' Throw an error message
                    MessageBox.Show("The Username/MachineName combination is either incorrect or not registered in the system..", "Authentication Failure", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)

                    'Focus on Username field
                    txtUsername.Focus()

                End If

                ' Close and dispose of the connection resource
                conn.Close()
                conn.Dispose()

            Catch ex As Exception
                MessageBox.Show("Failed to connect to Database..", "Database Connection Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
            End Try

        End If

    End Sub
any guidance in using a datareader and dbnulls?
I know how to check a data row for dbnull but since I'm not going that route leaves me at a lose.