如何控制，当某个字段等于特定值得时候不可以删除？

Alice

unit YWXX2;

interface

uses
  Business.System, Business.Model, Business.Data, Business.Forms;

type
  TYWXX2 = class(TInfo)
    DataSetBZSJJ1: TSQLDataSet;
    procedure DataSetBZSJJ1BeforeDelete(DataSet: TDataSet);
  private
    {private declarations}
    procedure DoDeleteError(DataSet: TAbstractDataSet; E: EDatabaseError;
      var Action: TDataAction);
  public
    {public declarations}
  end;

implementation


procedure TYWXX2.DataSetBZSJJ1BeforeDelete(DataSet: TDataSet);
begin
  if not DataSet.Fields[0].IsNull then
  begin
    DataSet.ReadOnly := True;
    DataSet.OnDeleteError := DoDeleteError;
  end;
end;

procedure TYWXX2.DoDeleteError(DataSet: TAbstractDataSet; E: EDatabaseError;
    var Action: TDataAction);
begin
  (DataSet as TDataSet).ReadOnly := False;
  E.Message := '不能删除';
end;

end.