求三个字段下,相同值的个数????怎么写代码?????

select count(course1&course2&course3) from student where (course1='"&course1&"'or course2='"&course1&"' or course3='"&course1&"')
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dim n //count()得到的数


if n>=150 then
response.write "<script language=JavaScript>" & chr(13) & "alert('该课已报满！');" & "history.back()" & "</script>"
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望高手指点赐教..............等待中......................thanks!!!!!!

另外还有什么方法,望高手不吝赐教.............
只要能解决问题...............