问题 填空题

数据库保护分为:安全性控制、______、并发性控制和数据的恢复。

答案

参考答案:完整性控制

解析: 安全性控制是防止未经授权的用户有意或无意存取数据库中的数据,以免数据被泄露、更改或破坏;完整性控制是保证数据库中数据及语义的正确性和有效性,防止任何对数据造成错误的操作;并发控制是正确处理好多用户、多任务环境下的并发操作,防止错误发生;数据的恢复是当数据库被破坏或数据不正确时,使数据库能恢复到正确的状态。

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Garden of small inventions

Visitors of all ages are invited to Port Discovery to see the new exhibit—a garden of small inventions, which features interactive activities and gadgets(小器械,小物件,小玩意) for the environmental protection. The exhibit runs through Sept.4. Fee is $10.75; free for ages younger than two. Contact 410-727-8120 or portdiscovery.org.

Rain-barrel workshop

The Parks and People Foundation presents a workshop on building water-efficient rain barrels for the home between 6pm-8pm on Wednesday at the foundation’s Stieff Silver Building. Cost is $50 and includes the barrel and all materials. Contact 410-448-5663, ext.109.

Pruning(修剪)plants

Visitors can attend a workshop on pruning plants between 9:30am-10am on Tuesday at Ladew Topiary Gardens. Visitors should meet in the Visitors Center at Ladew, Jarrettsville Pike, Monkton. $10; free for Ladew members, and includes admission to the gardens and the nature walk. Contact 410-557-9570 or www.ladewgardens.com.

Landscape exhibit

Photographs, paintings and drawings will be shown at Landscape and Nature—a view from Maryland, through Sept.9 at the University of Maryland. Opening reception is between 5pm-7:30pm on Tuesday. Contact 301-985-7937 or um.edu/art.

小题1:It will cost a couple with their newly-born baby________ to visit Port Discovery.

A.$ 30

B.$100

C.$21.5

D.nothing小题2:To learn how to make your flowers grow better, you will probably go to __________.

A.Port Discovery

B.Stieff Silver Building

C.Ladew Topiary Gardens

D.the University of Maryland小题3:You will call _______ to get information about learning something about art.

A.410-727-8120

B.410-448-5663

C.410-557-9570

D.301-985-7937小题4:Which activity is offered only on Wednesday according to the ads?

A.Garden of small inventions

B.Rain-barrel workshop

C.Pruning(修剪)plants

D.Landscape exhibit