【正文】 )，姓名 varchar(8)，年齡 int，專業(yè) varchar(20)，入學(xué)日期 DateTime）和 Score（ 學(xué)號 char(8)， 課程名 varchar(10),成績 numeric(5,2)）兩張表。 2. declare a numeric(5,2) set a=(select avg(成績 ) from score) select * from score where 成績 =a 答：從 Score 表中查詢出大于等于平均成績的所有記錄。 (每小題 2 分 ,共20 分 ) 1．設(shè) D D2和 D3域的基數(shù)分別為 3 和 4，則 D1?D2?D3的元組數(shù)為（ B）。 A. 學(xué)生號 B. 姓名 C. 性別 D. 年齡 3．設(shè)一個集合 A={3,4,5,6}，集合 B={1,3,5,7}，則 A 和 B 的并集中包含有（ D）個元素。 A. 傳遞性 B. 分解性 C. 合并性 D. 增廣性 5．在 SQL 的查詢語句中， order by 選項實現(xiàn)對結(jié)果表的（ D）功能。 A． dbf B． dbt C． mdb D． mdf 7． 在 Access 系統(tǒng)中 ， 對數(shù)據(jù)表的查詢操作共分為（ B）種情況。 A． B． C． D． 9． Access2021系統(tǒng)中包含有（ A）種數(shù)據(jù)類型。 A．窗體 B．報表 C．查詢 D．?dāng)?shù)據(jù)訪問頁 二、是非判斷題，根據(jù)敘述正確與否在題目開 始的括號內(nèi)打?qū)μ枴啊獭被虿嫣枴啊?(每小題 2 分 ,共 20 分 ) （ √ ） 1．在文件系統(tǒng)中，不容易做到數(shù)據(jù)共享，而在數(shù)據(jù)庫系統(tǒng)中，容易做到數(shù)據(jù)共享。 （ ） 3． 已知“職工號→性別”成立，則“（職工號，性別）→性別”是平凡函數(shù)依賴，但不是部分函數(shù)依賴。 （ ） 5．需求分析階段的主要目標(biāo)是畫出數(shù)據(jù)流圖和建立數(shù)據(jù)字典，不需要編 寫需求說明書。 （ ） 7. 在 SQL Server2021 中，不適合使用 bit 數(shù)據(jù)類型來表示邏輯數(shù)據(jù)。 （ ） 9. 在 SQL Server2021 中，多行注釋的開始標(biāo)記為“ /*”，結(jié)束標(biāo)記也為“ /*”。 三、填空題，把合適內(nèi)容填在橫線上。 2. 關(guān)系數(shù)據(jù)庫系統(tǒng)具有 （數(shù)據(jù)結(jié)構(gòu)） 單一、采用 （集合運算） 、數(shù)據(jù)完全獨立、數(shù)學(xué)理論支持等優(yōu)點。 4．在 SQL 中， （主碼） 約束的關(guān)鍵字為 primary key， （外碼） 約束的關(guān)鍵字為 foreign key。 6． SQL 是高度 （非過程化） 和面向 （集合） 操作的語言。 8．?dāng)?shù)據(jù)庫系統(tǒng)的 （三） 級模式結(jié)構(gòu)和 （兩） 級數(shù)據(jù)映象確保了數(shù)據(jù)的邏輯獨立性和物理獨立性。 10. 在 SQL 中 ，約束的關(guān)鍵字為 （單值） unique， （ 檢查 ） 約束的關(guān)鍵字為 check。 12．在 Access2021 的表結(jié)構(gòu)設(shè)計窗口中，其上半部分的“表設(shè)計器”是由字段 （名稱） 、數(shù)據(jù) （類型） 和說明等三列所組成。 14．在 Access2021 中，標(biāo)準(zhǔn)模塊包含的兩種過程是 （通用過程）和 （常用過程） 。 四、根據(jù)主教材第四章所給的商品庫和教學(xué)庫，按照下列前 3 小題的每條 SQL 查詢語句寫出相應(yīng)的功能，接著按照下列后 2 小題的每種功能寫出相應(yīng)的 SQL查詢語句。 2． select * from 課程 where exists (select 課程號 from 選課 where 課程 .課程號 =選課 .課程號 group by 課程號 having count(*)=3 ) 答：從教學(xué)庫中查詢出至少被 3 名學(xué)生選修的所有課程。 4．從商品庫中查詢出每 種商品的商品代號、單價、數(shù)量和產(chǎn)地。 答： select * from 商品表 1 where 數(shù)量 =some(select max(數(shù)量 ) from 商品表 1) //或者 where 數(shù)量 =all(select 數(shù)量 from 商品表 1) 五、根據(jù)下 面所給的 AAA數(shù)據(jù)庫，寫出每小題所能實現(xiàn)的功能。 1. create procedure xxk1 as begin select * from students x,score y where = end 答：顯示出 AAA 庫中所有學(xué)生的記錄信息及選課成績。 7 Visafree policy brings Chengdu biz, tourism boost. Making national headlines several times, Chengdu39。s level of internationalization. The policy will also bring direct economic revenue, Li said. Chengdu has many cultural legacies and is also a paradise for panda lovers with the world39。s ancient indigenous religion, while Du jiang yan is considered to be the oldest functioning watercontrol project in the world. Chengdu ranked third in tourist facilities, management and services among 60 Chinese cities in a customer satisfaction survey released last year. But, Li added that efforts are still needed to develop more tourism products, improve English services and provide accurate translation of traffic signs and scenic billboards. Zhao Yun, chairwoman of British Chamber of Commerce Southwest China, told China Daily that his colleagues found the policy very convenient. A British client once flew here and stayed for just one day to check her ordered goods, she said. Zhao was born in Shanxi province, but she has lived in Chengdu for more than 10 years. My life was like a running race moving from place to place. I also lived in Beijing and Shanghai before, she said. But Chengdu is a place that you never want to leave once settling down. It is now my second hometown, she said. If the environment is further improved, the city will attract more people to visit and live, with the 72hour visafree policy and pelling conditions in transportation, culture, climate and cuisine, he said. Foreigners also gave positive feedback on the policy. A spokesman from Dell Inc said the pany has a global hub of operation in Chengdu, so the threeday visa has an immediate and positive influence on the pany39。s public security bureau shows some 100 foreign visitors enjoyed the 72hour policy by the end of March, most of them from the United States, the United Kingdom and Germany. Chengdu also reported robust growth in its overall tourist industry last year. Official statistics show that it received some 150 million tourists last year, an increase of 28 percent from 2021. Around million came from abroad, an increase of 12 percent. Total revenue from tourism surpassed 133 billion yuan ($). During his visit to Kazakhstan in September, Chinese President Xi Jinping proposed that China and Central Asia join hands to build a Silk Road economic belt to boost cooperation. The idea has been w idely echoed in Central Asian countries, being an encouraging blueprint for Chinese areas along the Silk Road that has linked Asia and Europe for more than 2,000 years. In the next three weeks, China Daily reporters will travel through the belt in China and in Kazakhstan, Uzbekistan and Turkey. They w ill show the progress and expectations of the countries, businesses and peoples on the route. Shaanxi the start of the ancient Silk Road has positioned itself as the new starting point for the development of the Silk Road Economic Belt, w hich w ill strengthen China39。an. Lou held a joint interview with 27 media, including China Daily, the first in a series of interviews entitled Chinese Media Along the Silk Road. The interviews will be in Shaanxi and Gansu provinces and the Xinjiang Uygur autonomous region, as well as Kazakhstan, Uzbekistan and Turkey. The media group held the first interview on Wednesday morning in Xi3