[WebMethod(CacheDuration=45)]
public DataSet GetCustomers()
{
   SqlConnection conn;
   SqlDataAdapter myDataAdapter;
   DataSet myDataSet;
   string cmdString = "Select * From Customers";

   conn = new SqlConnection("Server=localhost;uid=sa;pwd=;database=Northwind");
   myDataAdapter = new SqlDataAdapter(cmdString, conn);

   myDataSet = new DataSet();
   myDataAdapter.Fill(myDataSet, "Customers");

   return myDataSet;
}