【正文】 user is also the very important information. The user may use the SQL sentence to visit the database data dictionary. Data Independence, Integrity, and Security Data Independence In database system, each program works with its own view or views of the database. If 畢業(yè)設(shè)計（論文）外文翻譯 6 new fields are added to a database record, the DBMS preserves the existing views so that existing programs don’t have to be changed. The ability to modify the structure of the database without affecting existing programs that refer to the database is called data independence Data Integrity Data integrity refers to the accuracy, correctness, or validity of the data in the database. In a database system, data integrity means safeguarding the data against invalid alteration or destruction. In large online database system, data integrity bees a more server problem. Data Security Data security refers to the protection of a database against unauthorized or illegal access or modification. This usually involves one or more level of password protection that is specified in the data dictionary. For example, a highlevel password might allow a user to read from, write to, and modify the database structure, whereas a lowlevel password might only allow a user to read from the database. Usually an audit trail, the recorded history of the modifications to a database, can be used to identify where and when a database was tampered with and it can also be used to restore the file to its original condition. 畢業(yè)設(shè)計（論文）外文翻譯 7 數(shù)據(jù)庫和數(shù)據(jù)倉庫 ？ 數(shù)據(jù)庫就是相關(guān)的數(shù)據(jù)項的集合。s information database growth statistics, the database performance statistics, the data character canonical is in the system each kind of data description set, carries on the main achievement which the detailed data collection and the data analysis obtain. The data dictionary usually includes the data item, the construction of data, the data stream, the data storage and the treating processes five parts. The data dictionary is about the data information set, is also all element definition set which contains to the data flow graph. Composes 1 data stream, 2 data stream ponents, namely the data element 3 data storages 4 process the database the important part is the data dictionaries. It deposits has the related information which the database uses, to the user is group of readonly tables. The data dictionary content includes: (1) database all pattern object information, like table, view, bunch, and index and so on. Assigns how many spaces, current has used how many spaces and so on. (2) row default value. (3) restraint information integrity. (4) user39。數(shù)據(jù)庫管理系統(tǒng)也提供其它的安全措施以防止非授權(quán)訪問。為了表明數(shù)據(jù)項之間的關(guān)系，通常有三種方法用于建立數(shù)據(jù)庫：關(guān)系數(shù)據(jù)庫、層次數(shù)據(jù)庫和網(wǎng)狀數(shù)據(jù)庫。因此，層次模型不能靈活地滿足信息要求改變的情況。 (3) 關(guān)系模型 在 20 世紀(jì) 70 年代早期發(fā)展關(guān)系數(shù)據(jù)庫是為了提供更多的對用戶友好的組織。 (1) 連接兩個關(guān)系（合并）。 Microsoft的 Access 是個人計算機(jī)關(guān)系數(shù)據(jù)庫管理系統(tǒng)。如果同時有很多數(shù)據(jù)庫用戶，那么服務(wù)器就會成為瓶頸，因此現(xiàn)在也有一種將更多的工作交給用戶的趨勢。包含在對象中的是完成每一項數(shù)據(jù)庫事務(wù)的處理指令。每一個節(jié)點(diǎn)是完全獨(dú)立的 —— 節(jié)點(diǎn)并不像它們在傳統(tǒng)數(shù)據(jù)庫中那樣 通過預(yù)先確定的組織方案聯(lián)系起來，而是由用戶自己建立節(jié)點(diǎn)間的連接。在大多數(shù)情況下，數(shù)據(jù)倉庫中的數(shù)據(jù)只可以用來進(jìn)行報告，不可進(jìn)行更新，所以公司的隱性操作系統(tǒng)的表現(xiàn)就沒有受到影響。多維數(shù)據(jù)分析的另外一項是在線分析過程（ LOAP）。組成 :1數(shù)據(jù)流 2數(shù)據(jù)流分量 即數(shù)據(jù)元素 3數(shù)據(jù)存儲 4處理數(shù)據(jù)庫的重要部分是數(shù)據(jù)字典。 (6) 用戶訪問或使用的審計信息。如果給數(shù)據(jù)記錄里加了新的域，數(shù)據(jù)庫管理系統(tǒng)就保存已有的視圖以便已有的程序不必改變。 通常，審計跟蹤記錄著數(shù)據(jù)庫修改歷史，可以用來指明數(shù)據(jù)庫被破壞的時間和地點(diǎn)，它也用于將文件復(fù)原。在大型聯(lián)機(jī)數(shù)據(jù)庫系統(tǒng)中，數(shù)據(jù)的完整性更加重要。數(shù)據(jù)庫 數(shù)據(jù)字典不僅是每個數(shù)據(jù)庫的中心。 (2) 列的缺省值。 數(shù)據(jù)字典是一個預(yù)留空間，一個數(shù)據(jù)庫，這是用來儲存信息數(shù)據(jù)庫本身。為了提供這種信息，組織可以用一種特殊化的多維數(shù)據(jù)庫，或用可以在關(guān)系數(shù)據(jù)庫中生成數(shù)據(jù) 的多維視圖的工具。數(shù)據(jù)倉庫是一種數(shù)據(jù)庫。面向?qū)ο髷?shù)據(jù)庫管理系統(tǒng)的好處就是它們支持 WWW應(yīng)用的能力。這樣就大大簡化了客戶端電腦載荷，減輕了系統(tǒng)維護(hù)與升級的成本和工作量，降低了用戶的總體成本（ TCO）。在最簡單的客戶 /服務(wù)器結(jié)構(gòu)中，除了查詢接口外整個數(shù)據(jù)庫管理系統(tǒng)都是服務(wù)器，查詢接口和用戶打交道并且發(fā)送查詢或其他命令給服務(wù)器。例如，一個叫 “ 賬目 ”的關(guān)系記錄銀行的賬目，它們的結(jié)余和類型如： 賬號 結(jié)余 類型