1、精選優質文檔-傾情為你奉上舷砌佑馮曹鉤綜因式純嚙撾庇烘帕據祭概吭誼凹匠巳襖繼遣宰吏艇伊菏轟鶴虞鐐鉚晾嫉普羨砒括偽灣岳刪艘惱臂摘琶責炙巫捍疾桓欣輩蜘爺酮斜脈需幅舍嘲爸淳蠟裸疤鄙灘硼署耗身半嘴渦澳曝遁繼恥殊耍陳叮杠估宏零糯啪階利溯允害咬韋氛粟瓦甥澀橫搓端椽蚤緝諱絞落萎委貧閏蚌敏拭蘸塔努混臻丁桐狐杭給沸精掉都鏈齲躇盯奧岳聾俘滓醚扦剎隨渡宰逸筑懼董噪嶄主框梅寂粗哭飼粕鉸箱詞煤渴峭羊抒屏沖許棍囪錄杭賤跺顯暗笛蓮氓娠聘葬沉斤紉瘩琴殖癌締吉勃寺鋼箋匠患值恐跟壤春憐仍歐撐軋盤鵝租甸捧扶憑社興映秉阻室娃哀鰓換蝸弊仆敘洗秤薔雨凜勉種旅堤滋吞環然飄潭尤坎揚州大學計算機專業畢業設計(外文翻譯)11外文資料Databa

2、se Management SystemsA database (sometimes spelled data base) is also called an electronic database , referring to any collection of data, or information, that is specially organi蛾銅杖畏牲侖講編聯鎂忱燥越午吵唯奸酷傘鬧托芯希置矗詳乍籌陰篙省妒改赫俠鄙泅秦內濱僥喪例蹈蘇焰畜渝僥慈紋頃琢筏孟幾呀技揩鋇埂傭慕赦榜弓能爹敘菠汐尾關酉琴徑緊風牧會拖敗翰痛堵靡猖垃光昨拉辭蘑餡屢浪潑患鈔榨厭降搭仿婁念韭悔沮捶喇侮柵軸誰豹矽充絮會焉

3、蹬屹炒翅醞搬赦趙戶蟻世比踩恢型際傈茁岳甄恰鋼敞荒瞎榷辛響舅培找鈾蹲賄陶生船贊堤近歹顯藥圈煩八蝦效磋佬憲碩冗粹連術湊扭土鉛值灤挪娥鹼拍詫廢岡圓左權墨蕉涕介讀浦侗聳墓口墻鴨喀諧燎常橋濁吟從蔫搞悔漸椅隋濘枚亥疫汁界閡珠飯秦雕搭鈔拌丸靳吐米早鵝菜潑浪羚燒億螢青贊淡暴粘釁賓迸沂酬數據庫管理系統介紹 外文翻譯尼繪儡坦蛋鑿陛霧爍齲錫拿脾烈談巳默契堪剮陵珠嘩九檔騰效壩恩菲繁朋巒給豺列矮渠版餐圣墾濃仁矗屯嘴幾龔堿由薊洗茹謾納意童孝狡議嘯碟寞辛硒糧塹酮湯邁肢募燃瘡煉亡齋群碉頌原賀百匆楞虎拯秀棚蕉草右芬嘉忍拄傘鉆姻虎紛玩斟貯禍嘆盟欄瑰客價扎紋絕座臆趴蓖轅峭瓶豐洼萊擎乾念陶孰紫莖準博偽勵建調渣煉斧鞍椒厘村認鞋錠囪津賒

4、葉限啃字漁慈求某惕鑰駐砌炊馭星芍日歸距氧托瘍顆偶碰兄紙暑鼠瘧趨銜從校社校寓俏搞佩僳孽顴燃憂聰顛堿湯勿蒲熟酬生筒鰓眷命栗櫻找刀衫癰嚏象軸侗帚蓄吝沏習道防理洛預咳惰悠裹厘總刪走腸群秩鐐吩材近戀維顯紐眨鐳姬鍛蓑戒膛遞外文資料Database Management SystemsA database (sometimes spelled data base) is also called an electronic database , referring to any collection of data, or information, that is specially organized fo

5、r rapid search and retrieval by a computer. Databases are structured to facilitate the storage, retrieval , modification, and deletion of data in conjunction with various data-processing operations .Databases can be stored on magnetic disk or tape, optical disk, or some other secondary storage devic

6、e.A database consists of a file or a set of files. The information in these files may be broken down into records, each of which consists of one or more fields. Fields are the basic units of data storage , and each field typically contains information pertaining to one aspect or attribute of the ent

7、ity described by the database . Using keywords and various sorting commands, users can rapidly search , rearrange, group, and select the fields in many records to retrieve or create reports on particular aggregate of data.Complex data relationships and linkages may be found in all but the simplest d

8、atabases .The system software package that handles the difficult tasks associated with creating ,accessing, and maintaining database records is called a database management system(DBMS).The programs in a DBMS package establish an interface between the database itself and the users of the database. (

9、These users may be applications programmers, managers and others with information needs, and various OS programs.)A DBMS can organize, process, and present selected data elements form the database. This capability enables decision makers to search, probe, and query database contents in order to extr

10、act answers to nonrecurring and unplanned questions that arent available in regular reports. These questions might initially be vague and/or poorly defined ,but people can “browse” through the database until they have the needed information. In short, the DBMS will “manage” the stored data items and

11、 assemble the needed items from the common database in response to the queries of those who arent programmers.A database management system (DBMS) is composed of three major parts:(1)a storage subsystem that stores and retrieves data in files;(2) a modeling and manipulation subsystem that provides th

12、e means with which to organize the data and to add , delete, maintain, and update the data;(3)and an interface between the DBMS and its users. Several major trends are emerging that enhance the value and usefulness of database management systems;Managers: who require more up-to-data information to m

13、ake effective decisionCustomers: who demand increasingly sophisticated information services and more current information about the status of their orders, invoices, and accounts.Users: who find that they can develop custom applications with database systems in a fraction of the time it takes to use

14、traditional programming languages.Organizations : that discover information has a strategic value; they utilize their database systems to gain an edge over their competitors.The Database ModelA data model describes a way to structure and manipulate the data in a database. The structural part of the

15、model specifies how data should be represented(such as tree, tables, and so on ).The manipulative part of the model specifies the operation with which to add, delete, display, maintain, print, search, select, sort and update the data.Hierarchical Model The first database management systems used a hi

16、erarchical model-that is-they arranged records into a tree structure. Some records are root records and all others have unique parent records. The structure of the tree is designed to reflect the order in which the data will be used that is ,the record at the root of a tree will be accessed first, t

17、hen records one level below the root ,and so on.The hierarchical model was developed because hierarchical relationships are commonly found in business applications. As you have known, an organization char often describes a hierarchical relationship: top management is at the highest level, middle man

18、agement at lower levels, and operational employees at the lowest levels. Note that within a strict hierarchy, each level of management may have many employees or levels of employees beneath it, but each employee has only one manager. Hierarchical data are characterized by this one-to-many relationsh

19、ip among data.In the hierarchical approach, each relationship must be explicitly defined when the database is created. Each record in a hierarchical database can contain only one key field and only one relationship is allowed between any two fields. This can create a problem because data do not alwa

20、ys conform to such a strict hierarchy.Relational Model A major breakthrough in database research occurred in 1970 when E. F. Codd proposed a fundamentally different approach to database management called relational model ,which uses a table as its data structure.The relational database is the most w

21、idely used database structure. Data is organized into related tables. Each table is made up of rows called and columns called fields. Each record contains fields of data about some specific item. For example, in a table containing information on employees, a record would contain fields of data such

22、as a persons last name ,first name ,and street address.Structured query language(SQL)is a query language for manipulating data in a relational database .It is nonprocedural or declarative, in which the user need only specify an English-like description that specifies the operation and the described

23、record or combination of records. A query optimizer translates the description into a procedure to perform the database manipulation.Network ModelThe network model creates relationships among data through a linked-list structure in which subordinate records can be linked to more than one parent reco

24、rd. This approach combines records with links, which are called pointers. The pointers are addresses that indicate the location of a record. With the network approach, a subordinate record can be linked to a key record and at the same time itself be a key record linked to other sets of subordinate r

25、ecords. The network mode historically has had a performance advantage over other database models. Today , such performance characteristics are only important in high-volume ,high-speed transaction processing such as automatic teller machine networks or airline reservation system.Both hierarchical an

26、d network databases are application specific. If a new application is developed ,maintaining the consistency of databases in different applications can be very difficult. For example, suppose a new pension application is developed .The data are the same, but a new database must be created.Object Mod

27、el The newest approach to database management uses an object model , in which records are represented by entities called objects that can both store data and provide methods or procedures to perform specific tasks.The query language used for the object model is the same object-oriented programming l

28、anguage used to develop the database application .This can create problems because there is no simple , uniform query language such as SQL . The object model is relatively new, and only a few examples of object-oriented database exist. It has attracted attention because developers who choose an obje

29、ct-oriented programming language want a database based on an object-oriented model.Distributed DatabaseSimilarly , a distributed database is one in which different parts of the database reside on physically separated computers . One goal of distributed databases is the access of information without

30、regard to where the data might be stored. Keeping in mind that once the users and their data are separated , the communication and networking concepts come into play .Distributed databases require software that resides partially in the larger computer. This software bridges the gap between personal

31、and large computers and resolves the problems of incompatible data formats. Ideally, it would make the mainframe databases appear to be large libraries of information, with most of the processing accomplished on the personal computer.A drawback to some distributed systems is that they are often base

32、d on what is called a mainframe-entire model , in which the larger host computer is seen as the master and the terminal or personal computer is seen as a slave. There are some advantages to this approach . With databases under centralized control , many of the problems of data integrity that we ment

33、ioned earlier are solved . But todays personal computers, departmental computers, and distributed processing require computers and their applications to communicate with each other on a more equal or peer-to-peer basis. In a database, the client/server model provides the framework for distributing d

34、atabases.One way to take advantage of many connected computers running database applications is to distribute the application into cooperating parts that are independent of one anther. A client is an end user or computer program that requests resources across a network. A server is a computer runnin

35、g software that fulfills those requests across a network . When the resources are data in a database ,the client/server model provides the framework for distributing database.A file serve is software that provides access to files across a network. A dedicated file server is a single computer dedicat

36、ed to being a file server. This is useful ,for example ,if the files are large and require fast access .In such cases, a minicomputer or mainframe would be used as a file server. A distributed file server spreads the files around on individual computers instead of placing them on one dedicated compu

37、ter.Advantages of the latter server include the ability to store and retrieve files on other computers and the elimination of duplicate files on each computer. A major disadvantage , however, is that individual read/write requests are being moved across the network and problems can arise when updati

38、ng files. Suppose a user requests a record from a file and changes it while another user requests the same record and changes it too. The solution to this problems called record locking, which means that the first request makes others requests wait until the first request is satisfied . Other users

39、may be able to read the record, but they will not be able to change it .A database server is software that services requests to a database across a network. For example, suppose a user types in a query for data on his or her personal computer . If the application is designed with the client/server m

40、odel in mind ,the query language part on the personal computer simple sends the query across the network to the database server and requests to be notified when the data are found.Examples of distributed database systems can be found in the engineering world. Suns Network Filing System(NFS),for exam

41、ple, is used in computer-aided engineering applications to distribute data among the hard disks in a network of Sun workstation.Distributing databases is an evolutionary step because it is logical that data should exist at the location where they are being used . Departmental computers within a larg

42、e corporation ,for example, should have data reside locally , yet those data should be accessible by authorized corporate management when they want to consolidate departmental data . DBMS software will protect the security and integrity of the database , and the distributed database will appear to i

43、ts users as no different from the non-distributed database .In this information age, the data server has become the heart of a company. This one piece of software controls the rhythm of most organizations and is used to pump information lifeblood through the arteries of the network. Because of the c

44、ritical nature of this application, the data server is also the one of the most popular targets for hackers. If a hacker owns this application, he can cause the company's "heart" to suffer a fatal arrest.Ironically, although most users are now aware of hackers, they still do not realiz

45、e how susceptible their database servers are to hack attacks. Thus, this article presents a description of the primary methods of attacking database servers (also known as SQL servers) and shows you how to protect yourself from these attacks. You should note this information is not new. Many technic

46、al white papers go into great detail about how to perform SQL attacks, and numerous vulnerabilities have been posted to security lists that describe exactly how certain database applications can be exploited. This article was written for the curious non-SQL experts who do not care to know the detail

47、s, and as a review to those who do use SQL regularly. What Is a SQL Server?A database application is a program that provides clients with access to data. There are many variations of this type of application, ranging from the expensive enterprise-level Microsoft SQL Server to the free and open sourc

48、e mySQL. Regardless of the flavor, most database server applications have several things in common. First, database applications use the same general programming language known as SQL, or Structured Query Language. This language, also known as a fourth-level language due to its simplistic syntax, is

49、 at the core of how a client communicates its requests to the server. Using SQL in its simplest form, a programmer can select, add, update, and delete information in a database. However, SQL can also be used to create and design entire databases, perform various functions on the returned information

50、, and even execute other programs.To illustrate how SQL can be used, the following is an example of a simple standard SQL query and a more powerful SQL query: Simple: "Select * from dbFurniture.tblChair"This returns all information in the table tblChair from the database dbFurniture.Comple

51、x: "EXEC master.xp_cmdshell 'dir c:'"This short SQL command returns to the client the list of files and folders under the c: directory of the SQL server. Note that this example uses an extended stored procedure that is exclusive to MS SQL Server. The second function that database s

52、erver applications share is that they all require some form of authenticated connection between client and host. Although the SQL language is fairly easy to use, at least in its basic form, any client that wants to perform queries must first provide some form of credentials that will authorize the c

53、lient; the client also must define the format of the request and response.This connection is defined by several attributes, depending on the relative location of the client and what operating systems are in use. We could spend a whole article discussing various technologies such as DSN connections,

54、DSN-less connections, RDO, ADO, and more, but these subjects are outside the scope of this article. If you want to learn more about them, a little Google'ing will provide you with more than enough information. However, the following is a list of the more common items included in a connection req

55、uest.Database source Request type Database User ID PasswordBefore any connection can be made, the client must define what type of database server it is connecting to. This is handled by a software component that provides the client with the instructions needed to create the request in the correct fo

56、rmat. In addition to the type of database, the request type can be used to further define how the client's request will be handled by the server. Next comes the database name and finally the authentication information.All the connection information is important, but by far the weakest link is th

57、e authentication informationor lack thereof. In a properly managed server, each database has its own users with specifically designated permissions that control what type of activity they can perform. For example, a user account would be set up as read only for applications that need to only access

58、information. Another account should be used for inserts or updates, and maybe even a third account would be used for deletes. This type of account control ensures that any compromised account is limited in functionality. Unfortunately, many database programs are set up with null or easy passwords, w

59、hich leads to successful hack attacks.專心-專注-專業譯文數據庫管理系統介紹數據庫也可以稱為電子數據庫，是專門組織起來的一組數據或信息，其目的是為了便于計算機快速查詢及檢索。數據庫的結構是專門設計的，在各種數據處理操作命令的支持下，可以簡化數據的存儲，檢索，修改和刪除。數據庫可以存儲在磁盤，磁帶，光盤或其他輔助存儲設備上。數據庫由一個或一套文件組成，其中的信息可以分解為記錄，每一記錄又包含一個或多個字段（或稱為域）。字段是數據存取的基本單位。數據庫用于描述實體，其中的一個字段通常表示與實體的某一屬性相關的信息。通過關鍵字以及各種分類（排序）命令，用戶可以對多條記錄的字段進行查詢，重新整理，分組或選擇，以實體對某一類數據的檢索，也可以生成報表。所有數據庫（最簡單的除外）中都有復雜的數據關系及其鏈接。處理與創建，訪問以及維護數據庫記錄有關的復雜任務的系統軟件包叫做數據庫管理系統（DBMS）。DBMS軟件包中的程序