[Yurk@@@]

Спасибо, всё работает!!!
var date1,date2:TDateTime;
...
Date1:=DateTimePicker1.Date;
Date2:=DateTimePicker2.Date;
Query3.SQL.Text:='select field1,field2,field3 from table where field1 between "'+DateToStr(date1)+'" and "'+DateToStr(date2)+'"' ;