type
  TContact = class
  private
    FId: integer;
    FName: string;
    FCountry: TCountry;
  public
    property Id: integer read FId write FId;
    property Name: string read FName write FName;
    property Country: TCountry read FCountry write FCountry;
  end;

// Get all contacts
MyContacts := Manager.Find<TContact>.List;

// Get name of country of first contact:
FirstContactCountryName := MyContacts[0].Country.Name;

SELECT A.ID AS A_ID, A.NAME AS A_NAME, A.COUNTRY_ID AS A_COUNTRY_ID, B.ID AS B_ID, B.NAME AS B_NAME
FROM CONTACT A LEFT JOIN COUNTRY B ON (B.ID = A.COUNTRY_ID)

type
  TContact = class
  private
    FId: integer;
    FName: string;
    FCountry: Proxy<TCountry>;
    function GetCountry: TCountry;
    procedure SetCountry(const Value: TCountry);
  public
    property Id: integer read FId write FId;
    property Name: string read FName write FName;
    property Country: TCountry read GetCountry write SetCountry;
  end;

function TContact.GetCountry: TCountry;
begin
  Result := FCountry.Value;
end;

procedure TContact.SetCountry(const Value: TCountry);
begin
  FCountry.Value := Value;
end;

SELECT A.ID AS A_ID, A.NAME AS A_NAME, A.COUNTRY_ID AS A_COUNTRY_ID 
FROM CONTACT A

SELECT A.ID AS A_ID, A.NAME AS A_NAME
FROM COUNTRY A

// Get all contacts and countries at once,
// regardless of lazy-load mode in mapping
MyContacts := Manager.Find<TContact>
  .CreateAlias('Country', 'c', TFetchMode.Eager)
  .List;

// Get name of country of first contact:
FirstContactCountryName := MyContacts[0].Country.Name;