数据库课堂测验.docx

景世超计科三班终极预测【基于课堂作业】******************************** 【考试题预测】****************************** 1 、给相应的文字描述写出先关的操作! (第 2章) 【必考】【给个例题】 Consider the relational database of Figure , where the primary keys are un- derlined. Give an expression in the relational algebra to express each of the fol- lowing queries: a. Find the names of all employees who work for First Bank Corporation. b. Find the names and cities of residence of all employees who work for First Bank Corporation. c. Find the names, street address, and cities of residence of all employees who work for First Bank Corporation and earn more than $10,000 per annum. d. Find the names of all employees in this database who live in the same city as pany for which they work. e. Assume panies may be located in several cities. Find panies located in every city in which Small Bank Corporation is located. employee (person-name, street, city) works (person-name, company-name, salary) company (company-name, city) manages (person-name, manager-name) Figure . Relational database for Exercises , and . Answer: person-name (pany-name =“ First Bank Corporation ”(works)) 【例题 2】 Consider the relational database of Figure . Give an expression in the rela- tional algebra for each request: a. Give all employees of First Bank Corporation a 10 percent salary raise. 景世超计科三班 b. Give allmanagers in this database a 10 percent s