--if object_id('CHENGJI') is not null drop table CHENGJI
--create table CHENGJI
--(
--    id int NOT NULL,
--    chengji int NOT NULL,
--    xingming varchar(30) NOT NULL,
--    banji int NOT NULL
--)
--insert CHENGJI
--select 1,90,'张三',14 union
--select 2,70,'李四',17 union
--select 3,80,'张三',14 union
--select 4,60,'张三',14 union
--select 5,77,'李四',17 union
--select 6,80,'张三',14 union
--select 7,90,'李四',17 union
--select 8,70,'李四',17 
--go

declare @Sql varchar(300)
declare @chengji int
Set @chengji=80
Set @Sql=' Select id,chengji,xingming ,banji  From CHENGJI  Where chengji='+cast(@Chengji as varchar(10))
Print(@Sql)
exec(@Sql)

procedure TForm1.Button1Click(Sender: TObject);
begin
  ADOQuery1.Close;
  ADOQuery1.SQL.Clear;
  ADOQuery1.SQL.Add('Select id,chengji,banji,xingming From CHENGJI where chengji=80');
  ADOQuery1.Open;
  Memo1.Lines.Clear;
  While ADOQuery1.Eof =false do
  begin
    Memo1.Lines.Add(ADOQuery1.FieldByName('id').AsString);
    Memo1.Lines.Add(IntToStr(ADOQuery1.FieldByName('chengji').AsInteger));
    Memo1.Lines.Add(ADOQuery1.FieldByName('xingming').AsString);
    Memo1.Lines.Add(ADOQuery1.FieldByName('banji').AsString);
    ADOQuery1.Next;
  end;
  ADOQuery1.Close;
end;