cn.ConnectionString = "Data Source=.SQLEXPRESS;AttachDbFilename=C:Documents and SettingsiaprubillosMy DocumentsPROJECTmyProjectdatabasemyDatabase.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True"

cn.ConnectionString = "Data Source=|DataDirectory|myDatabase.mdf"

cn.ConnectionString = String.format("Data Source=.SQLEXPRESS;AttachDbFilename={0}myDatabase.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True", My.Application.Info.DirectoryPath)