说明： 利用XML作为数据源的轻量级数据库，方便小型数据的应用和XML的学习。
(The use of XML as a data source lightweight database for small applications and XML data learning.)
文件列表：
LightWeightDB
.............\LightWeightDB
.............\.............\bin
.............\.............\...\Debug
.............\.............\...\.....\LightWeightDB.dll
.............\.............\...\.....\LightWeightDB.pdb
.............\.............\...\Release
.............\.............\...\.......\LightWeightDB.dll
.............\.............\...\.......\LightWeightDB.pdb
.............\.............\DatabaseException.cs
.............\.............\IItemList.cs
.............\.............\ItemBase.cs
.............\.............\ItemsBase.cs
.............\.............\Key.cs
.............\.............\LightWeightDB.csproj
.............\.............\obj
.............\.............\...\Debug
.............\.............\...\.....\LightWeightDB.dll
.............\.............\...\.....\LightWeightDB.pdb
.............\.............\...\.....\Refactor
.............\.............\...\.....\........\LightWeightDB.dll
.............\.............\...\.....\TempPE
.............\.............\...\LightWeightDB.csproj.FileList.txt
.............\.............\...\Release
.............\.............\...\.......\LightWeightDB.dll
.............\.............\...\.......\LightWeightDB.pdb
.............\.............\...\.......\Refactor
.............\.............\...\.......\........\LightWeightDB.dll
.............\.............\...\.......\TempPE
.............\.............\Properties
.............\.............\..........\AssemblyInfo.cs
.............\LightweightDB Article.html
.............\LightWeightDB.sln
.............\TestLightWeightDB
.............\.................\bin
.............\.................\...\Debug
.............\.................\...\.....\Books.xml
.............\.................\...\.....\LightWeightDB.dll
.............\.................\...\.....\LightWeightDB.pdb
.............\.................\...\.....\TestLightWeightDB.exe
.............\.................\...\.....\TestLightWeightDB.pdb
.............\.................\...\.....\TestLightWeightDB.vshost.exe
.............\.................\...\Release
.............\.................\...\.......\LightWeightDB.dll
.............\.................\...\.......\LightWeightDB.pdb
.............\.................\...\.......\TestLightWeightDB.exe
.............\.................\...\.......\TestLightWeightDB.pdb
.............\.................\Books.cs
.............\.................\obj
.............\.................\...\Debug
.............\.................\...\.....\Refactor
.............\.................\...\.....\ResolveAssemblyReference.cache
.............\.................\...\.....\TempPE
.............\.................\...\.....\TestLightWeightDB.exe
.............\.................\...\.....\TestLightWeightDB.pdb
.............\.................\...\Release
.............\.................\...\.......\Refactor
.............\.................\...\.......\ResolveAssemblyReference.cache
.............\.................\...\.......\TempPE
.............\.................\...\.......\TestLightWeightDB.exe
.............\.................\...\.......\TestLightWeightDB.pdb
.............\.................\...\TestLightWeightDB.csproj.FileList.txt
.............\.................\Program.cs
.............\.................\Properties
.............\.................\..........\AssemblyInfo.cs
.............\.................\TestLightWeightDB.csproj
