講述計(jì)算機(jī)DBMS的編排技巧的英語(yǔ)
英語(yǔ)和計(jì)算機(jī)是對(duì)于我們的生活都很經(jīng)常用的東西了，所以小編今天就給大家整理了有關(guān)于計(jì)算機(jī)的英語(yǔ)，大家要閱讀一下哦
計(jì)算機(jī)英語(yǔ)
sequential 順序的，連續(xù)的
integrate 綜合，使成整體
access v. 訪問
retrieve v.找回，檢索
employ v.使用
list structure n.鏈表結(jié)構(gòu)
invoice n. 發(fā)票
pointer n.指針
hierarchical structure 樹結(jié)構(gòu)
subordinate adj. 從屬的
network structure 網(wǎng)狀結(jié)構(gòu)
relational structure 關(guān)系結(jié)構(gòu)
physical structure 物理結(jié)構(gòu)
Abbreviations:
DBMS(Database Management System) 數(shù)據(jù)庫(kù)管理信息系統(tǒng)
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(gè)文件的數(shù)據(jù)項(xiàng)以回答用戶對(duì)信息的查詢，這就意味著DBMS能夠訪問和檢索非關(guān)鍵記錄字段的數(shù)據(jù)，即DBMS能夠?qū)讉€(gè)大文件中邏輯相關(guān)的數(shù)據(jù)組織并連接在一起。
Logical Structures. Identifying these logical relationships is a job of the data administrator. A data definition language is used for this purpose. The DBMS may then employ one of the following logical structuring techniques during storage access, and retrieval operations [1]:
邏輯結(jié)構(gòu)。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。DBMS在存儲(chǔ)、訪問和檢索操作過程中可選用以下邏輯構(gòu)造技術(shù):
1. List structures. In this logical approach, records are linked together by the use of pointers. A pointer is a data item in one record that identifies the storage location of another logically related record. Records in a customer master file, for example, will contain the name and address of each customer, and each record in this file is identified by an account number. During an accounting period, a customer may buy a number of items on different days. Thus, the company may maintain an invoice file to reflect these transactions.
鏈表結(jié)構(gòu)。在該邏輯方式中，記錄通過指針鏈接在一起。指針是記錄中的一個(gè)數(shù)據(jù)項(xiàng)，它指出另一個(gè)邏輯相關(guān)的記錄的存儲(chǔ)位置，例如，顧客主文件中的記錄將包含每個(gè)顧客的姓名和地址，而且該文件中的每個(gè)記錄都由一個(gè)賬號(hào)標(biāo)識(shí)。在記賬期間，顧客可在不同時(shí)間購(gòu)買許多東西,公司保存一個(gè)發(fā)票文件以反映這些交易。
A list structure could be used in this situation to show the unpaid invoices at any given time. Each record in the customer file would contain a field that would point to the record location of the first invoice for that customer in the invoice file (fig11-1). This invoice record, in turn, would be linked to later invoices for the customer. The last invoice in the chain would be identified by the use of a special character as a pointer.
這種情況下可使用鏈表結(jié)構(gòu)，以顯示給定時(shí)間內(nèi)未支付的發(fā)票。顧客文件中的每個(gè)記錄都包含這樣一個(gè)字段，該字段指向發(fā)票文件(圖11-1)中該顧客的第一個(gè)發(fā)票的記錄位置，該發(fā)票記錄又依次與該顧客的下一個(gè)發(fā)票記錄相連，此鏈接的最后一個(gè)發(fā)票記錄由一個(gè)作為指針的特殊字符標(biāo)識(shí)。
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