SqlDataAdapter Fill Method: System.OutOfMemoryException exception

hello sir,

below is my select query

 public void AccountFilter1()
    {
        con.Open();
        SqlDataAdapter adpt = new SqlDataAdapter("select CompanyName, Website, Phone_No, Address, City, State, Zip, All_Countries, All_Industries, All_SubIndustries, Employees, All_Company_Size, Revenue, All_Company_Revenue ,ROW_NUMBER() over (partition by Website ORDER BY CompanyName, Website, Phone_No, Address, City, State, Zip, All_Countries, All_Industries, All_SubIndustries, Employees, All_Company_Size, Revenue, All_Company_Revenue) RowNumber from testCompany", con);
        DataTable dt = new DataTable();
        adpt.Fill(dt);
        gridCompany.Visible = true;
        gridContact.Visible = false;
        gridCompany.DataSource = dt;
        gridCompany.DataBind();
        con.Close();
    }

i want to find and fetch dupliactes from database and bind in in gridview fro 1000 data its working but above that getting "System.OutOfMemoryException" exception

plz help