问题 问答题


阅读以下说明,回答问题1~4。
[说明]
设某商业集团数据库中有三个实体集。一是“仓库”实体集,属性有仓库号、仓库名和地址等;二是“商店”实体集,属性有商店号、商店名、地址等;三是“商品”实体集,属性有商品号、商品名、单价。设仓库与商品之间存在“库存”联系,每个仓库可存储若干种商品,每种商品存储在若干仓库中,每个仓库每存储一种商品有日期及存储量;商店与商品之间存在着“销售”联系,每个商店可销售若干种商品,每种商品可在若干商店里销售,每个商店销售一种商品有月份和月销售量两个属性;仓库、商店、商品之间存在着“供应”联系,有月份和月供应量两个属性。

[问题2]
将ER图转换成关系模型,并说明主键和外键。

答案

参考答案:

解析:据转换规则,图2的ER图可转换成6个关系模式;仓库(仓库号,仓库名,地址)商品(商品号,商品名,单价)商店(商店号,商店名,地址)库存(仓库号商品号,日期,库存量)销售(商店号商品号,月份,月销售量)供应(仓库号高店号高品号,月份,月供应量)

选择题
单项选择题

Remember the days when companies such as Microsoft and Mc-Kinsey took immense satisfaction from subjecting job candidates to mind-crunching strategy sessions If you thought that was rough, imagine an interview in which no amount of research or questioning of insiders will help. Imagine instead that all you can do is have a healthy breakfast, pick out your nicest suit, and hope for the best. In the new interview, they’re not just testing what you know. They’re also testing who you are.

It’s called the situational interview, and it’s quickly becoming a must in the job-seeking world. In the post-Enron culture of caution, corporations are focusing on an obvious insight: that a gold-plated resume and winning personality are about as accurate in determining job performance as Wall Street analysts are in picking stocks. Now, with shareholder scrutiny, hiring slowdowns, and expense-reducing, no manager can afford to hire the wrong person. Hundreds of companies are switching to the new methods. Whereas the conventional interview has been found to be only 7% accurate in predicting job performance, situational interviews deliver a rating of 54%—the most of any interviewing tool.

The situational technique’s superiority stems from its ability to trip up even the wittiest of interviewees. Of course, every applicant must display a healthy dose of occupational know-how, but behavior and ethical backbone play a big role. For example, a prospective analyst at a Wall Street bank might have to face, say, a customer with an account argument. It’s not happening on paper, but in real time—with managers and experts watching nearby. The interviewer plays the role of a fierce customer on the phone, angry about money lost when a trade wasn’t executed on time. It’s set up as an obvious mistake on the banker’s part.

Interviewers watch the candidates’ reactions: how they process the complex account information, their ability to talk the client down, what their body language displays about their own shortcomings, and which words they choose. In this instance, not being honest about the mistake or showing anger or frustration—no matter how glowing your resume—means you’re out.

Behavioral interviews are also being rounded out by other tools that, until recently, had been reserved for elite hires. Personality-testing outfit Caliper, for example, which probes candidates for emotional-intelligence skills and job ability, has seen its business jump 20% this year.

Clearly, the new interview isn’t without its drawbacks. Companies run the risk of arousing hostility in candidates, who may feel as if some line has been crossed into personal territory. Moreover, sortie companies worry about the fairness of personality tests. They have to make sure there are no inherent gender or racial biases in the test.

The situational interview is superior to the conventional in its ().

A.capability to catch the smartest applicants in misjudgments

B.possibility to lead the wisest candidates to behavioral mistakes

C.technique to make the cleverest interviewees be inaccurate

D.function to frustrate the brightest individuals by hard questions