[求助]ADV 试题一道

是 否 +2 论坛币

k人 参与回答

经管之家送您一份

应届毕业生专属福利!

求职就业群

赵安豆老师微信：zhaoandou666

经管之家联合CDA

送您一个全额奖学金名额~ !

立即领取

感谢您参与论坛问题回答

经管之家送您两个论坛币！

+2 论坛币

为什么A不对?

Suppose that the Sasuser.Revenue data set has a simple index named FlightID. For which of the following programs will the index be used? a. proc print data=sasuser.revenue; where flightid ne 'IA11200'; run; b. data someflights; set sasuser.revenue; where flightid > 'IA11200'; run; c. data someflights; set sasuser.revenue; if flightid > 'IA11200'; run; d. proc print data=sasuser.revenue; where origin='RDU' or flightid='IA03400'; run; Correct answer: &lt;script&gt;<br>document.write(correctAns[9])<br>&lt;/script&gt; 复制代码 b

扫码加我 拉你入群

请注明：姓名-公司-职位

以便审核进群资格，未注明则拒绝

分享0 收藏0 回帖

关键词：following programs Document Revenue sasuser 求助 试题 adv

It's a confusing question.

I think, if dataset has many obs (say 100 or more, actually, Sasuser.Revenue has 142 obs, but we can't think this particular dataset, should be general, right?), using 'ne', SAS needs to process more obs then this specifical one 'IA11200' , so not effienct?

But, on the other hand, if 'IA11200' is the smallest one in the dataset, so where flightid > 'IA11200' is similar to where flightid ne 'IA11200', right? Both answer A and B are not correct? no answer for this question.

The explanation from the answer also confusing, did not mention A either:

An index can improve the efficiency with which SAS is able to access certain observations in a data set. However, an index is not always useful. SAS will not use an index to process subsetting IF statements, or other statements that SAS determines might be more efficiently processed without an index.