計(jì)算機(jī)專(zhuān)業(yè)英語(yǔ)電子教案第11章-wenkub
2023-05-21 14:32:37 本頁(yè)面
【正文】 : facilitate 使容易 ， 促進(jìn) retrieval n. 檢索 field n. 字段 ， record 記錄 ， alphabetically 按字母順序地 chronologically 按年代順序排 break down v. 分解 build up 建造 ， 裝配 ， 組成 encyclopedia n. 百科全書(shū) reference n. 涉及 ， 參考 ， 引用 bibliography 書(shū)目 ， 參考書(shū)目 periodical n. 期刊 ， 雜志 literature n. 文獻(xiàn) ， 著作 professional n. 專(zhuān)業(yè)人員 ， 專(zhuān)家 Overview Abbreviations: Chapter 11 Database Management 計(jì)算機(jī)專(zhuān)業(yè)英語(yǔ) 115 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 entity described by the database. Using keywords and various sorting mands, users can rapidly search, rearrange, group, and select the fields in many records to retrieve or create reports on particular aggregates of data. 一個(gè)數(shù)據(jù)庫(kù)由一個(gè)文件或文件集合組成 。 這些文件中的信息可分解成一個(gè)個(gè)記錄 ， 每個(gè)記錄有一個(gè)或多個(gè)域 。 the development of directaccess storage devices made possible random access to data via indexes. Queries are the main way users retrieve database information. Typically, the user provides a string of characters, and the puter searches the database for a corresponding sequence and provides the source materials in which those characters appear. A user can request, for example, all records in which the content of the field for a person’s last name is the word Smith. 數(shù)據(jù)庫(kù)記錄和文件的組織必須確保能對(duì)信息進(jìn)行檢索 。 比如 ， 用戶(hù)能夠在所有記錄中尋找所有 last name域?yàn)?Smith的記錄 。 層次型數(shù)據(jù)庫(kù)按樹(shù)型組織記錄 ， 每一層的記錄分解成更小的屬性集 。 a simple flat list bees one table, or “relation”, and multiple relations can be mathematically associated to yield desired information. Objectoriented databases store and manipulate more plex data structures, called “objects”, which are anized into hierarchical classes that may inherit properties from classes higher in the chain。 面向?qū)ο蟮臄?shù)據(jù)庫(kù)存儲(chǔ)并處理更復(fù)雜的稱(chēng)為對(duì)象的數(shù)據(jù)結(jié)構(gòu) ， 可組織成有層次的類(lèi) ， 其中的每個(gè)類(lèi)可以繼承層次鏈中更高一級(jí)類(lèi)的特性 ， 這種數(shù)據(jù)庫(kù)結(jié)構(gòu)最靈活 ，最具適應(yīng)性 。 確定這些邏輯關(guān)系是數(shù)據(jù)管理者的任務(wù) ， 由數(shù)據(jù)定義語(yǔ)言完成 。 在記賬期間 ， 顧客可在不同時(shí)間購(gòu)買(mǎi)許多東西 ,公司保存一個(gè)發(fā)票文件以反映這些交易 。s a superiorsubordinate relationship in a hierarchical (tree) structure. Below the singleroot data ponent are subordinate elements or nodes, each of which, in turn, own one or more other elements (or none) [3]. Each element or branch in this structure below the root has only a single owner. Thus, as we see in fig112, a customer owns an invoice, and the invoice has subordinate items. The branches in a tree structure are not connected. 層次 (樹(shù)型 )結(jié)構(gòu) 。 在樹(shù)型結(jié)構(gòu)中 ， 樹(shù)枝不能相連 。 Chapter 11 Database Management 計(jì)算機(jī)專(zhuān)業(yè)英語(yǔ) 1116 Oracle的數(shù)據(jù)庫(kù)管理功能 New Words amp。 論文摘要是全文的精華 ， 是對(duì)一項(xiàng)科學(xué)研究工作的總結(jié) ， 對(duì)研
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