how to add the rows to the datatable while executereader reads the rows from the table?

Question

I want to add the rows that are read by executereader to the new datatable with C# coding

Answer 1

There are too many unknowns in your question. Foreg, is the data table typed or untyped? What are the column types? And so forth.

But anyway, here's a general example. I adapted the code from the original sample given here.

private static void ReadOrderData(string connectionString)
{
    string queryString = "SELECT OrderID, CustomerID FROM dbo.Orders;";

    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        SqlCommand command = new SqlCommand(queryString, connection);
        connection.Open();

        SqlDataReader reader = command.ExecuteReader();

        // Call Read before accessing data.
        while (reader.Read())
        {
           CustomersRow newCustomersRow = Customers.NewCustomersRow();
           newCustomersRow.CustomerID = reader[0].ToString();
           newCustomersRow.CompanyName = reader[1].ToString();
           dt.Rows.Add(newCustomersRow);
        }

        // Call Close when done reading.
        reader.Close();
    }
}