OleDbConnection db_baglanti = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath("~/App_Data/vt.mdb"));

db_baglanti.Open();
OleDbCommand db_komut = new OleDbCommand();
db_komut.CommandText = "select * from duyurular";
db_komut.Connection = db_baglanti;
OleDbDataReader dr = db_komut.ExecuteReader();
GridView1.DataSource = dr;
GridView1.DataBind();