加一个自动编号字段(中间不要断号),则:
SELECT a.id, a.地点, a.频点
FROM 表1 AS a
WHERE a.id in (select b.id from 表1 as b where b.地点=a.地点 and b.id =Int((DMax("id","表1","地点='" & [地点] & "'") - DMin("id","表1","地点='" & [地点] & "'") + 1) * Rnd + DMin("id","表1","地点='" & [地点] & "'")));