You know that a database is a collection of logically related data elements that may be structured in various ways to meet the multiple processing and retrieva l needs of organizations and individuals．There’ s nothing new about databases—early ones[1] were chiseled in stone，penned on scrolls，and written on index cards．But now databases are commonly recorded on magnetizable media，and computer programs are required to perform the necessary storage and retrieva l operations．
You’ll see in the following pages that complex data relationships and linkages may be found in all but the simplest databases[2]．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．（These users may be applications programmers，managers and others with information needs，and various OS programs．）
眾所周知，數(shù)據(jù)庫是邏輯上相關(guān)的數(shù)據(jù)元的匯集。這些數(shù)據(jù)元可以按不同的結(jié)構(gòu)組織起來，以滿足單位和個人的多種處理和檢索的需要。數(shù)據(jù)庫本身不是什么新鮮事—一早期的數(shù)據(jù)庫鑿在石頭上，記在名冊上，以及寫在索引卡中。而現(xiàn)在，數(shù)據(jù)庫普遍記錄在可磁化的介質(zhì)上，并且需要用計算機程序來執(zhí)行必需的存儲和檢索操作。
如下所述，所有數(shù)據(jù)庫（最簡單的除外）中都有復雜的數(shù)據(jù)關(guān)系及其鏈接。處理與創(chuàng)建、訪問以及維護數(shù)據(jù)庫記錄有關(guān)的復雜任務(wù)的系統(tǒng)軟件包叫做數(shù)據(jù)庫管理系統(tǒng)（DBMS）。DBMS軟件包中的程序在數(shù)據(jù)庫與其用戶間建立接口。（這些用戶可以是應(yīng)用程序員、管理員、及其他需要信息的人員和各種操作系統(tǒng)程序）。