我們?cè)陧?xiàng)目中要求將實(shí)體的所有修訂（更改歷史記錄）存儲(chǔ)在數(shù)據(jù)庫中。目前，我們有2個(gè)為此設(shè)計(jì)的提案：例如，對(duì)于“雇員”實(shí)體設(shè)計(jì)1：-- Holds Employee Entity"Employees (EmployeeId, FirstName, LastName, DepartmentId, .., ..)"-- Holds the Employee Revisions in Xml. The RevisionXML will contain-- all data of that particular EmployeeId"EmployeeHistories (EmployeeId, DateModified, RevisionXML)"設(shè)計(jì)2：-- Holds Employee Entity"Employees (EmployeeId, FirstName, LastName, DepartmentId, .., ..)"-- In this approach we have basically duplicated all the fields on Employees -- in the EmployeeHistories and storing the revision data."EmployeeHistories (EmployeeId, RevisionId, DateModified, FirstName,       LastName, DepartmentId, .., ..)"還有其他方法可以做到這一點(diǎn)嗎？“設(shè)計(jì)1”的問題在于，每次需要訪問數(shù)據(jù)時(shí)，我們都必須解析XML。這將減慢該過程的速度，并增加一些限制，例如我們無法在修訂數(shù)據(jù)字段上添加聯(lián)接?！霸O(shè)計(jì)2”的問題在于，我們必須在所有實(shí)體上重復(fù)每個(gè)字段（我們要維護(hù)其大約70-80個(gè)實(shí)體的修訂版）。