【正文】 ture 物理結(jié)構(gòu) DBMS STRUCTURING TECHNIQUES Abbreviations : DBMS（ Database Management System） 數(shù)據(jù)庫管理信息系統(tǒng) Chapter 11 Database Management 計算機專業(yè)英語 1110 DBMS STRUCTURING TECHNIQUES DBMS is able to access and retrieve data from nonkey record fields. That is, the DBMS is able to structure and tie together the logically related data from several large files. DBMS可綜合幾個文件的數(shù)據(jù)項以回答用戶對信息的查詢 ， 這就意味著 DBMS能夠訪問和檢索非關鍵記錄字段的數(shù)據(jù) ， 即 DBMS能夠?qū)讉€大文件中邏輯相關的數(shù)據(jù)組織并連接在一起 。 面向?qū)ο蟮臄?shù)據(jù)庫存儲并處理更復雜的稱為對象的數(shù)據(jù)結(jié)構(gòu) ， 可組織成有層次的類 ， 其中的每個類可以繼承層次鏈中更高一級類的特性 ， 這種數(shù)據(jù)庫結(jié)構(gòu)最靈活 ，最具適應性 。 一個表或一個 “ 關系 ” ， 就是一個簡單的非結(jié)構(gòu)列表 。 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。 網(wǎng)絡型數(shù)據(jù)庫的速度及多樣性使其在企業(yè)中得到廣泛應用 。 層次型數(shù)據(jù)庫按樹型組織記錄 ， 每一層的記錄分解成更小的屬性集 。 many simple databases for personal puters are flat in structure. The records in hierarchical databases are anized in a treelike structure, with each level of records branching off into a set of smaller categories. Unlike hierarchical databases, which provide single links between sets of records at different levels, work databases create multiple linkages between sets by placing links, or pointers, to one set of records in another。 比如 ， 用戶能夠在所有記錄中尋找所有 last name域為 Smith的記錄 。 用戶檢索數(shù)據(jù)庫信息的主要方法是 query(查詢 )。 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)庫記錄和文件的組織必須確保能對信息進行檢索 。 用戶使用鍵盤和各種排序命令 ， 能夠快速查找 、 重排 、 分組并在查找的許多記錄中選擇相應的域 ， 建立特定集上的報表 。 這些文件中的信息可分解成一個個記錄 ， 每個記錄有一個或多個域 。Computer English Chapter 11 Database Management Chapter 11 Database Management 計算機專業(yè)英語 112 Key points: useful terms and definitions of Database Management Difficult points: Classification of the logical structuring techniques of DBMS Chapter 11 Database Management 計算機專業(yè)英語 113 Requirements: 1. Principle of easiest peration 2. The kinds of puter security breaches 3. What is firewall 4. 了解 英文摘要的寫作技巧 Chapter 11 Database Management 計算機專業(yè)英語 114 New Words amp。 Expressions: facilitate 使容易 ， 促進 retrieval n. 檢索 field n. 字段 ， record 記錄 ， alphabetically 按字母順序地