SpinEdit1、 SpinEdit2分别是分数查询的上限和下限，Achievement是成绩表，怎么出错？(5分)

提示SpinEdit1和SpinEdit2没有默认值，怎么回事？
procedure TFAcjdkcx.SpeedButton1Click(Sender: TObject);
begin
with Fdm.AQ_adkcjcx do
begin
close;
sql.Clear;
sql.Add('select * from Achievement');
sql.Add('where Achievement between SpinEdit1.TEXT and SpinEdit2.TEXT');
open;
end;
end;

改为：
sql.Add('where Achievement between '+SpinEdit1.TEXT+' and '+SpinEdit2.TEXT');

谢谢这位eyangyj先生

接受答案了.