Dim ligacao_codigo As SqlConnection = New SqlConnection(str_ligacao)
ligacao_codigo.Open()
Dim Select_codigo As SqlCommand = New SqlCommand(" Select Count(*)from TabPedido ", ligacao_codigo)
Dim codigo_dr As SqlDataReader
codigo_dr = Select_codigo.ExecuteReader
codigo_dr.Read()
' garda o num de registos que existem na tabela
codigo = codigo_dr(0).ToString
cod = Val(codigo)