c# - How to fill a custom typed List<> from SQL Server -

i have class named author.cs defined as:

public class author : interfaces.inode {     private list<inode> _targetlist;     private list<iattribute> _attributeobject;      // author class constructor     public author()     {         _targetlist = new list<inode>();     }     //implementazion of _targetobject inode method     public list<inode> _targetobject     {                 {              return _targetlist;         }     }     //implementazion of _attributeobject inode method     public list<iattribute> _attributeobject     {                 {              return _attributeobject;         }     }      public int _aid { get; set; }     public string _aname { get; set; }       // 'coauthor', 'venue' , 'paper' classes       // implements interface i.e. `iattribute`     public list<coauthor> _acoauthors { get; set; }      public list<venue> _avenue { get; set; }     public list<paper> _apapers { get; set; }     public string _aarea { get; set; } }   

which implements interface in interfaces folder named interfaces.inode.cs defined as:

public interface inode {     list<inode> _targetobject { get; }     list<iattribute> _attributeobject { get; } }  public interface iattribute : inode {}   

now want fill list i.e. list<author> i.e. in class named authorcollector.cs

list<author> _eathors = new list<author>();   

i have tried as:

try {     sqlcommand _mycommand_1 = _con.createcommand();     _mycommand_1.commandtext = @"select author_id m_datafull                                    order author_id, year";     var _authid = 0;     int _row_counter = 0;      using (sqldatareader _myreader_1 = _mycommand_1.executereader())     {         while (_myreader_1.read())         {             _row_counter++;             _eathors.add(convert.toint32(_myreader_1["author_id"]));         }         _myreader_1.close();      } } catch(exception e) {      console.writeline(e.message); }   

the error is:
the best overloaded method match _eauthors.add() has invalid arguments.
please in regard.

using (sqldatareader _myreader_1 = _mycommand_1.executereader()) {     while (_myreader_1.read())     {        _row_counter++;        author author = new author();        author._aid = convert.toint32(_myreader_1["author_id"]);        author._aname = convert.tostring(_myreader_1["author_name"]);        //etc...        _eathors.add(author);     }     _myreader_1.close(); }