Return List from SqlDataReader using C# in ASP.Net

Hi nauna,

Refer the below code.

public List<Country> GetCountry()
{
    string sqlStatment = "select countryid, countryname from country";
    string constr = System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
    using (System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection(constr))
    {
        using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(sqlStatment, con))
        {
            cmd.Connection.Open();
            System.Data.SqlClient.SqlDataReader reader = cmd.ExecuteReader();
            List<Country> emp = new List<Country>();
            while (reader.Read())
            {
                Country country = new Country();
                country.countryid = Convert.ToInt32(reader.GetValue(0));
                country.countryname = reader.GetValue(1).ToString();
                emp.Add(country);
            }

            reader.Close();
            cmd.Connection.Close();
            return emp;
        }
    }
}

public class Country
{
    public int countryid { get; set; }
    public string countryname { get; set; }
}

OR

public List<Country> GetCountry()
{
    string sqlStatment = "select countryid, countryname from country";
    string constr = System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
    using (System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection(constr))
    {
        using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(sqlStatment, con))
        {
            cmd.Connection.Open();
            System.Data.SqlClient.SqlDataReader reader = cmd.ExecuteReader();
            List<Country> emp = new List<Country>();
            while (reader.Read())
            {
                Country country = new Country
                {
                    countryid = Convert.ToInt32(reader.GetValue(0)),
                    countryname = reader.GetValue(1).ToString()
                };

                emp.Add(country);
            }

            reader.Close();
            cmd.Connection.Close();
            return emp;
        }
    }
}

public class Country
{
    public int countryid { get; set; }
    public string countryname { get; set; }
}

You are returning List<Country> So your method should returns List<Country>.