[cvcvcv]

الجملة الأولى
& Public cn As New SqlConnection("Data Source=.\SQLEXPRESS;AttachDbFilename=" & Application.StartupPath
("\database_tarek.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True

الجملة الثانية
\Public cn As New SqlConnection("Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\bin\Debug
("\database_tarek.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True

الجملة الثالثة
(Public cn As New SqlConnection(My.Settings.database_tarekConnectionString