using parameters in query string [resolved]

[angelica]

Hi,

My error states that I should be declaring @checkBook. I am assuming I am declaring it in [RED] so where's the mistake pls???

Also do I need to use an adapter in here cos I had a search and found this method but I am assuming I need to state my connection somewhere right?? How's that??

Also if someone knows of any good link where I could learn more about parameters please send me link.

many thanks

Private Sub CurrentBalanceShowD()
        Dim cmd As New SqlCommand

        Try
            cmd.Parameters.AddWithValue("@checkBook", SqlDbType.Int).Value = cboBookD.SelectedValue            cmd.Parameters.AddWithValue("@checkBook", bookFID)


            MyConn.Open()    'opening the connection
            cmd = New SqlCommand("Select stockBalance from tb_bookbalance where bookFID = @checkBook", MyConn) 'executing the command and assigning it to connection 

            txtcurrentD.Text = (cmd.ExecuteScalar()).ToString   'displaying the data from the table
            MyConn.Close()
        Catch ex As Exception
            MsgBox(ex.Message)
            MyConn.Close()
        End Try
    End Sub