Try This...
SqlConnection con = new SqlConnection("Data Source=(local);Database=UrDatabaseName;uid=sa;pwd=sa");
con.Open();
string Query = "Select * from Employee";
SqlDataAdapter da = new SqlDataAdapter(Query, con);
DataTable DT = new DataTable();
da.Fill(DT);
GridView2.DataSource = DT;
GridView2.DataBind();