boyinyu的专栏

2009年全国硕士研究生入学统一考试 英语试题 　　大作文是：网络的近与远 　　一 客观描述图 　　二 说明意思 　　三 给出观点 　　【范文】 　　As is vividly depicted in the drawing, in front of computers and in narrow spaces are sitting many people, exchanging their views with each other by surfing the Internet. How impressive the drawing is in describing the people’s addiction to the Internet. The drawer’s intention seems to be highly self-evident and the meaning causes us to be thought-provoking.

解法一：SELECT TNAME,DEPART FROM TEACHER A LEFT JOIN COURSE B USING(TNO) WHERE ISNUL (B.tno); 解法二：select tname,depart from teacher a where not exists (select * from course b where a.tno=b.tno); 解法三：SELECT TNAME,DEPART FROM TEACHER WHERE TNO NOT IN (SELECT TNO FROM COURSE); NOT IN的方法效率最差，其余两种差不多