FbCommand, queries: dúvida de iniciante

var
  command: fbcommand;
  fb: FbConnection;
  dr: FbDataReader;
begin
try
  try
    fb := FbConnection1;
    fb.Open;
    command:= fbcommand.Create;
    command.Connection:= Fb;
    command.CommandText:= ´SELECT * FROM PLANOSAUDE WHERE IDPLANO = ?´;
    command.Parameters.Add(´@IDPLANO´,DbType.String);

    command.Parameters[´@IDPLANO´].Value := _IdPlano;

    dr:= command.ExecuteReader;
    If dr.Read then begin //Essa linha verifica se encontrou registros
      IdPlano := dr.Item[´IDPLANO´].ToString;
      Descricao := dr.Item[´DESCRICAO´].ToString;
      Status := dr.Item[´STATUS´].ToString;
    end;
    dr.Close;
    command.Dispose;
  finally
    Fb.Close;
  end;