public class Mapping {
public static T Entity<T>(IDataReader reader,Dictionary<string,int> dictionary) {
var type = typeof(T);
//T u = new T();
        T u = Activator.CreateInstance<T>();

        PropertyInfo[] field =  type.GetProperties();
int index = -1;
foreach (var f in field) {
if (dictionary.TryGetValue(f.Name, out index)) {
var r = reader.GetValue(index);
if(r != DBNull.Value)
            f.SetValue(u, r, null);
        }
        }
return u;
    }
}

Dictionary<string, int> dictionary = new Dictionary<string, int>();

var dr = cmd.ExecuteReader();
int count = dr.FieldCount;
for (int i = 0; i < count; i++) {
    dictionary.Add(dr.GetName(i), i);
}

public List<T> findAll<T>() {
var list = new List<T>();
//var parame = new List<QueryParameter>();
//parame.Add("uid");
    Dictionary<string, int> dictionary = new Dictionary<string, int>();
using (SqlConnection conn = new SqlConnection(sqlConnectionString)) {
    String sql = "SELECT uid,username FROM Users ORDER BY uid DESC";

    SqlCommand cmd = new SqlCommand(sql, conn);
//SqlParameter p = new SqlParameter("@uid", 1);
//cmd.Parameters.Add(p);

    conn.Open();

var dr = cmd.ExecuteReader();
int count = dr.FieldCount;
for (int i = 0; i < count; i++) {
        dictionary.Add(dr.GetName(i), i);
    }

while (dr.Read()) {
        list.Add(Mapping.Entity<T>(dr,dictionary));
    }

    dr.Close();
    conn.Close();
    }
return list;
}