【正文】 SQL 的交互性使它最適合用來快速回答特定詢問語句。它正迅速成為在相關(guān)數(shù)據(jù)庫中存取數(shù)據(jù)的標(biāo)準(zhǔn)詢問語言。 ） 管理信息系統(tǒng)（ MIS） 一個 MIS 可定義為一個基于計算機(jī)的數(shù)據(jù)處理過程的網(wǎng)絡(luò)系統(tǒng)，一個機(jī)構(gòu)為了支持決策及其他必須的管理功能，以便提供及時有效的信息，開發(fā)了這一系統(tǒng)；若需要，手工操作與其過程也在該系統(tǒng)中結(jié)合在一起了。 目前，數(shù)據(jù)庫管理系統(tǒng)有 4 種主要的基本結(jié)構(gòu)，它們是： 表結(jié)構(gòu)。數(shù)據(jù)結(jié)構(gòu)的任何變化要求所有的應(yīng)用程序作相應(yīng)的變化。 當(dāng)一個數(shù)據(jù)庫管理系統(tǒng)被使用時，有關(guān)數(shù)據(jù)管理組織的詳細(xì)情況不必建立在每一個應(yīng)用程序中。數(shù)據(jù)庫事務(wù)是一組視作整體的數(shù)據(jù)庫修改工作，如一個旅行社代理人預(yù)定一個航班，預(yù)約就包括幾個數(shù)據(jù)庫的修改（即增加乘 客的姓名和地址，并修改可用作為字段）這些修改組成了一個事務(wù)。 數(shù)據(jù)完整性指數(shù)據(jù)庫中數(shù)據(jù)的精確度、正確性或合法性。 在有關(guān)歷史研究的數(shù)據(jù)管理中，一個必要的研究課題是定量的分析使用直接支持時間屬性的數(shù)據(jù)庫系統(tǒng)合使用不支持時間屬性的常見數(shù)據(jù)庫系統(tǒng)之間的性能（甚至效率）差別數(shù)據(jù)。在給定的時間間隔，就會產(chǎn)生一次查詢，即為該特定時間間隔而檢索歷史數(shù)據(jù)。時間數(shù)據(jù)管理方面的麻煩是：應(yīng)用和數(shù)據(jù)庫系統(tǒng)之間的界限還沒有劃清楚，特別是時間數(shù)據(jù)管理的典型語義和設(shè)備由多少能夠且應(yīng)該直接合并在數(shù)據(jù)庫系統(tǒng)中，有多少應(yīng)該留給應(yīng)用和用戶，還不十分清楚。 DBMS 結(jié)構(gòu)技術(shù) 二十年來空間數(shù)據(jù)管理一直是數(shù)據(jù)庫研究的活躍區(qū)，研究的焦點(diǎn)集中在發(fā)展存儲 和索引空間數(shù)據(jù)的數(shù)據(jù)結(jié)構(gòu)上。事實(shí)上，數(shù)據(jù)庫系統(tǒng)唯一重要的方向是數(shù)據(jù)獨(dú)立性。從使用意圖的性質(zhì)看，這些機(jī)器上的數(shù)據(jù)庫系統(tǒng)中沒有正式數(shù)據(jù)庫的一些要求。只有當(dāng)一組程序?yàn)槊恳粋€數(shù)據(jù)進(jìn)入和更新功能定制客戶規(guī)格是，才有可能得到這些控制。在面向文件的系統(tǒng)中，需要特定信息的用戶可以將他們的要求傳送給那些程序員，該程序員在時間允許時，將編寫一個或多個程序以提取數(shù)據(jù)和準(zhǔn)備信息。 數(shù)據(jù)庫管理信息系統(tǒng)可組織、處理和顯示從數(shù)據(jù)庫中選擇的數(shù)據(jù)元素。然而，作為通用的數(shù)據(jù)庫術(shù)語常常是有一些限制的，數(shù)據(jù)庫有下列內(nèi)在的性質(zhì)： ? 數(shù)據(jù)庫是在邏輯上緊密相關(guān)的并且有某種內(nèi)在意義的集合，隨機(jī)的數(shù)據(jù)組合不能稱為數(shù)據(jù)庫； ? 數(shù)據(jù)庫是為某種特定目的而設(shè)計、建議和聚集的數(shù)據(jù)，它有一些預(yù)期的用戶和這些用戶感興趣的某些預(yù)想的應(yīng)用； ? 數(shù)據(jù)庫表示實(shí)際世界某一方面，有時也叫做“微 型世界”，對微型世界的改變反映在數(shù)據(jù)庫中。例如，所有你知道的人的名字、電話號碼和地址，可以在一個索引地址簿中記錄，或者可以用個人衛(wèi)星計算機(jī)及諸如 dBASE Ⅲ 或 Lotus 123 這樣的軟件把它們記錄在軟盤上。在這些情況下，信息的潛在價值沒有實(shí)現(xiàn)，因?yàn)槠渌块T需要它的人卻不知道這些信息，或者不能有效地訪問這些信息。如果一個系統(tǒng)在結(jié)構(gòu)上完全分離，則它們被稱為包含一個數(shù)據(jù)庫集合。 they utilize their database systems to gain an edge over their petitors. A DBMS can anize, process, and present selected data elements from the database. This capability enables decision makers to search, probe, and query data base contents in order to extract answers to nonrecurring and unplanned questions that aren’t 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 “mange” the stored data items and assemble the needed items from the mon database in response to the queries of those who aren’t programmers. In a fileoriented system, user needing special information may municate their needs to a programmer, who, when time permits, will write one or more programs to extract the data and prepare the information. The availability of a DBMS, however, offers users a much faster alternative munications path. DATABASE QUERY If the DBMS provides a way to interactively enter and update the database ,as well as interrogate it ,this capability allows for managing personal database. However, it does not automatically leave an audit trail of actions and does not provide the kinds of controls necessary in a multiuser anization .There controls are only available when a set of application programs is customized for each data entry and updating function. Software for personal puters that perform some of the DBMS functions has been very popular .Individuals for personal information storage and processing intended personal puters for us .Small enterprises, professionals like doctors, architects, engineers, lawyers and so on have also used these machines extensively. By the nature of intended usage ,database system on there machines are except from several of the requirements of fullfledged database systems. Since data sharing is not intended, concurrent operations even less so ,the software can be less plex .Security and integrity maintenance are deemphasized or absent .as data volumes will be small, performance efficiency is also less important .In fact, the only aspect of a database system that is important is data independence. Data independence ,as stated earlier ,means that application programs and user