关于SQL？？

ClientDataSet1.Close;
ClientDataSet1.CommandText:='Select * From SYS_OPERATORS Where OPTID=admin';
ClientDataSet1.Execute;
delphi总提示我：“ADOQuery1:can not perform this operation on a open dataset”
为什么？？Execute是对于数据库有所修改的时候用的～～
查询用Ｏｐｅｎ
ClientDataSet1.Close;
ClientDataSet1.CommandText:='Select * From SYS_OPERATORS Where OPTID=admin';
ClientDataSet1.Open;