Evitar insertar datos al actualizar página.

[Bibliotec]

Si aqui tienes el codigo si te sirve:

Sub cli(Sender As Object, E As EventArgs)
if ispostback() then
Dim cnn As OleDbConnection
Dim cmd AS OleDbCommand
Dim strsmt As String
strsmt ="INSERT INTO cliente (nombre, codigo) VALUES (@login, @password)"
cnn = New OleDBConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" & Server.MapPath("cliente1.mdb;"))

cmd = New OleDbCommand(strsmt,cnn)
cmd.Parameters.Add(New OleDbParameter("@login", TextBox1.text))
cmd.Parameters.Add(New OleDbParameter("@password", TextBox2.text))
cnn.open()
cmd.ExecuteNonQuery()
cnn.close()
end if
TextBox1.Text = ""
TextBox2.Text = ""


End Sub