如何将多个表的结果显示为一个？

Question

这是我的代码，但结果是空白的。

SELECT TOP 1 grade_el.grade_ID, time_el.time_id, subjects_el.IDno, subjects_el.subj_name 
FROM grade_el,
     subjects_el,
     scheduling_el,
     time_el
WHERE grade_el.grade_ID = 1 
  AND time_el.time_id = 0001
  AND subjects_el.subj_name <> scheduling_el.subj_name 
ORDER BY rnd(subjects_el.IDno)

请有人帮助我。