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让EF飞一会儿:如何用Entity Framework 6 连接Sqlite数据库

时间：2021-07-01 10:21:17 帮助过：24人阅读

获取Sqlite

1.可以用NuGet程序包来获取，它也会自动下载EF6

技术分享

2.在Sqlite官网上下载对应的版本：http://system.data.sqlite.org/index.html/doc/trunk/www/downloads.wiki

注意这里面每个.net framework都有两个版本，一个带有bundle字眼，一个没有。一个安装的DLL里面包含SQLite.Interop.dll，而另一个没有。如果你运行代码的时候报

“无法加载SQLite.Interop.dll”的错误，则将安装文件中的SQLite.Interop.dll拷贝到Bin文件中即可。或是在NuGet下载的packages\System.Data.SQLite.Core.1.0.94.0\build中也有对应的程序。

示例代码

Model.cs

  1. <span style="color: #0000ff">   public</span> <span style="color: #0000ff">class</span><span style="color: #000000"> Person
  2.     {
  3.         </span><span style="color: #0000ff">public</span> Int64 Id { <span style="color: #0000ff">get</span>; <span style="color: #0000ff">set</span>; } <span style="color: #008000">//</span><span style="color: #008000">注意要用Int64</span>
  4.         <span style="color: #0000ff">public</span> <span style="color: #0000ff">string</span> FirstName { <span style="color: #0000ff">get</span>; <span style="color: #0000ff">set</span><span style="color: #000000">; }
  5.         </span><span style="color: #0000ff">public</span> <span style="color: #0000ff">string</span> LastName { <span style="color: #0000ff">get</span>; <span style="color: #0000ff">set</span><span style="color: #000000">; }
  6.     }
  7.     </span><span style="color: #0000ff">public</span> <span style="color: #0000ff">class</span><span style="color: #000000"> MyContext : DbContext
  8.     {
  9.         </span><span style="color: #0000ff">public</span> DbSet<Person> Persons { <span style="color: #0000ff">get</span>; <span style="color: #0000ff">set</span><span style="color: #000000">; }
  10.         </span><span style="color: #0000ff">public</span><span style="color: #000000"> MyContext()
  11.             : </span><span style="color: #0000ff">base</span>(<span style="color: #800000">"</span><span style="color: #800000">SqliteTest</span><span style="color: #800000">"</span><span style="color: #000000">)
  12.         {
  13.         }
  14.     }</span>

Program.cs

  1.  <span style="color: #0000ff">static</span> <span style="color: #0000ff">void</span> Main(<span style="color: #0000ff">string</span><span style="color: #000000">[] args)
  2.         {
  3.             MyContext context </span>= <span style="color: #0000ff">new</span><span style="color: #000000"> MyContext();
  4.             </span><span style="color: #0000ff">var</span> empList = context.Persons.OrderBy(c =><span style="color: #000000"> c.FirstName).ToList();
  5.             Console.WriteLine(empList.Count);
  6.             Person people </span>= <span style="color: #0000ff">new</span><span style="color: #000000"> Person()
  7.             {
  8.                 FirstName </span>= <span style="color: #800000">"</span><span style="color: #800000">Hello</span><span style="color: #800000">"</span><span style="color: #000000">,
  9.                 LastName </span>= <span style="color: #800000">"</span><span style="color: #800000">World</span><span style="color: #800000">"</span><span style="color: #000000">
  10.             };
  11.             context.Persons.Add(people);
  12.             context.SaveChanges();
  13.             Console.ReadLine();
  14.         }</span>

示例代码很简单，就是用EF对Person表进行新增与查看。

配置config文件

如果你是用NuGet获取Sqlite，会自动在config中配置一些相关的信息。

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  1. <span style="color: #0000ff"><?</span><span style="color: #ff00ff">xml version="1.0" encoding="utf-8"</span><span style="color: #0000ff">?></span>
  2. <span style="color: #0000ff"><</span><span style="color: #800000">configuration</span><span style="color: #0000ff">></span>
  3.   <span style="color: #0000ff"><</span><span style="color: #800000">configSections</span><span style="color: #0000ff">></span>
  4.     <span style="color: #008000"><!--</span><span style="color: #008000"> For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 </span><span style="color: #008000">--></span>
  5.     <span style="color: #0000ff"><</span><span style="color: #800000">section </span><span style="color: #ff0000">name</span><span style="color: #0000ff">="entityFramework"</span><span style="color: #ff0000"> type</span><span style="color: #0000ff">="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"</span><span style="color: #ff0000"> requirePermission</span><span style="color: #0000ff">="false"</span> <span style="color: #0000ff">/></span>
  6.   <span style="color: #0000ff"></</span><span style="color: #800000">configSections</span><span style="color: #0000ff">></span>
  7.    <span style="color: #0000ff"><</span><span style="color: #800000">connectionStrings</span><span style="color: #0000ff">></span>
  8.     <span style="color: #0000ff"><</span><span style="color: #800000">add </span><span style="color: #ff0000">name</span><span style="color: #0000ff">="SqliteTest"</span><span style="color: #ff0000"> connectionString</span><span style="color: #0000ff">="data source=SqliteTest.db"</span><span style="color: #ff0000"> providerName</span><span style="color: #0000ff">="System.Data.SQLite.EF6"</span> <span style="color: #0000ff">/></span>
  9.   <span style="color: #0000ff"></</span><span style="color: #800000">connectionStrings</span><span style="color: #0000ff">></span>
  10.   <span style="color: #0000ff"><</span><span style="color: #800000">startup</span><span style="color: #0000ff">></span>
  11.     <span style="color: #0000ff"><</span><span style="color: #800000">supportedRuntime </span><span style="color: #ff0000">version</span><span style="color: #0000ff">="v4.0"</span><span style="color: #ff0000"> sku</span><span style="color: #0000ff">=".NETFramework,Version=v4.5"</span> <span style="color: #0000ff">/></span>
  12.   <span style="color: #0000ff"></</span><span style="color: #800000">startup</span><span style="color: #0000ff">></span>
  13.   <span style="color: #0000ff"><</span><span style="color: #800000">system.data</span><span style="color: #0000ff">></span>
  14.     <span style="color: #0000ff"><</span><span style="color: #800000">DbProviderFactories</span><span style="color: #0000ff">></span>
  15.       <span style="color: #0000ff"><</span><span style="color: #800000">add </span><span style="color: #ff0000">name</span><span style="color: #0000ff">="SQLite Data Provider"</span><span style="color: #ff0000"> invariant</span><span style="color: #0000ff">="System.Data.SQLite"</span><span style="color: #ff0000"> description</span><span style="color: #0000ff">=".NET Framework Data Provider for SQLite"</span><span style="color: #ff0000"> type</span><span style="color: #0000ff">="System.Data.SQLite.SQLiteFactory, System.Data.SQLite"</span> <span style="color: #0000ff">/></span>
  16.       <span style="color: #0000ff"><</span><span style="color: #800000">remove </span><span style="color: #ff0000">invariant</span><span style="color: #0000ff">="System.Data.SQLite"</span> <span style="color: #0000ff">/></span>
  17.       <span style="color: #0000ff"><</span><span style="color: #800000">remove </span><span style="color: #ff0000">invariant</span><span style="color: #0000ff">="System.Data.SQLite.EF6"</span> <span style="color: #0000ff">/></span>
  18.       <span style="color: #0000ff"><</span><span style="color: #800000">add </span><span style="color: #ff0000">name</span><span style="color: #0000ff">="SQLite Data Provider (Entity Framework 6)"</span><span style="color: #ff0000"> invariant</span><span style="color: #0000ff">="System.Data.SQLite.EF6"</span><span style="color: #ff0000"> description</span><span style="color: #0000ff">=".NET Framework Data Provider for SQLite (Entity Framework 6)"</span><span style="color: #ff0000"> type</span><span style="color: #0000ff">="System.Data.SQLite.EF6.SQLiteProviderFactory, System.Data.SQLite.EF6"</span> <span style="color: #0000ff">/></span>
  19.     <span style="color: #0000ff"></</span><span style="color: #800000">DbProviderFactories</span><span style="color: #0000ff">></span>
  20.   <span style="color: #0000ff"></</span><span style="color: #800000">system.data</span><span style="color: #0000ff">></span>
  21.   <span style="color: #0000ff"><</span><span style="color: #800000">entityFramework</span><span style="color: #0000ff">></span>
  22.     <span style="color: #0000ff"><</span><span style="color: #800000">defaultConnectionFactory </span><span style="color: #ff0000">type</span><span style="color: #0000ff">="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework"</span><span style="color: #0000ff">></span>
  23.       <span style="color: #0000ff"><</span><span style="color: #800000">parameters</span><span style="color: #0000ff">></span>
  24.         <span style="color: #0000ff"><</span><span style="color: #800000">parameter </span><span style="color: #ff0000">value</span><span style="color: #0000ff">="v11.0"</span> <span style="color: #0000ff">/></span>
  25.       <span style="color: #0000ff"></</span><span style="color: #800000">parameters</span><span style="color: #0000ff">></span>
  26.     <span style="color: #0000ff"></</span><span style="color: #800000">defaultConnectionFactory</span><span style="color: #0000ff">></span>
  27.     <span style="color: #0000ff"><</span><span style="color: #800000">providers</span><span style="color: #0000ff">></span>
  28.       <span style="color: #0000ff"><</span><span style="color: #800000">provider </span><span style="color: #ff0000">invariantName</span><span style="color: #0000ff">="System.Data.SqlClient"</span><span style="color: #ff0000"> type</span><span style="color: #0000ff">="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer"</span> <span style="color: #0000ff">/></span>
  29.       <span style="color: #0000ff"><</span><span style="color: #800000">provider </span><span style="color: #ff0000">invariantName</span><span style="color: #0000ff">="System.Data.SQLite.EF6"</span><span style="color: #ff0000"> type</span><span style="color: #0000ff">="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6"</span> <span style="color: #0000ff">/></span>
  30.     <span style="color: #0000ff"></</span><span style="color: #800000">providers</span><span style="color: #0000ff">></span>
  31.   <span style="color: #0000ff"></</span><span style="color: #800000">entityFramework</span><span style="color: #0000ff">></span>
  32. <span style="color: #0000ff"></</span><span style="color: #800000">configuration</span><span style="color: #0000ff">></span>
View Code

其中数据连接串是：

  1.    <span style="color: #0000ff"><</span><span style="color: #800000">add </span><span style="color: #ff0000">name</span><span style="color: #0000ff">="SqliteTest"</span><span style="color: #ff0000"> connectionString</span><span style="color: #0000ff">="data source=SqliteTest.db"</span><span style="color: #ff0000"> providerName</span><span style="color: #0000ff">="System.Data.SQLite.EF6"</span> <span style="color: #0000ff">/></span>

注意提供程序集是System.Data.SQLite.EF6。

但是这个配仍然是错误的。

如果此时运行程序，会报错：

Unable to determine the provider name for provider factory of type ‘System.Data.SQLite.SQLiteFactory‘. Make sure that the ADO.NET provider is installed or registered in the application config.

或中文错误信息：

未找到具有固定名称“System.Data.SQLite”的 ADO.NET 提供程序的实体框架提供程序。请确保在应用程序配置文件的“entityFramework”节中注册了该提供程序。

意思是EF没有找到提供System.Data.SQLite.SQLiteFactory的dll，我们看看现在config中的entityFramework节点：

  1.   <span style="color: #0000ff"><</span><span style="color: #800000">entityFramework</span><span style="color: #0000ff">></span>
  2.     <span style="color: #0000ff"><</span><span style="color: #800000">defaultConnectionFactory </span><span style="color: #ff0000">type</span><span style="color: #0000ff">="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework"</span><span style="color: #0000ff">></span>
  3.       <span style="color: #0000ff"><</span><span style="color: #800000">parameters</span><span style="color: #0000ff">></span>
  4.         <span style="color: #0000ff"><</span><span style="color: #800000">parameter </span><span style="color: #ff0000">value</span><span style="color: #0000ff">="v11.0"</span> <span style="color: #0000ff">/></span>
  5.       <span style="color: #0000ff"></</span><span style="color: #800000">parameters</span><span style="color: #0000ff">></span>
  6.     <span style="color: #0000ff"></</span><span style="color: #800000">defaultConnectionFactory</span><span style="color: #0000ff">></span>
  7.     <span style="color: #0000ff"><</span><span style="color: #800000">providers</span><span style="color: #0000ff">></span>
  8.       <span style="color: #0000ff"><</span><span style="color: #800000">provider </span><span style="color: #ff0000">invariantName</span><span style="color: #0000ff">="System.Data.SqlClient"</span><span style="color: #ff0000"> type</span><span style="color: #0000ff">="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer"</span> <span style="color: #0000ff">/></span>
  9.       <span style="color: #0000ff"><</span><span style="color: #800000">provider </span><span style="color: #ff0000">invariantName</span><span style="color: #0000ff">="System.Data.SQLite.EF6"</span><span style="color: #ff0000"> type</span><span style="color: #0000ff">="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6"</span> <span style="color: #0000ff">/></span>
  10.     <span style="color: #0000ff"></</span><span style="color: #800000">providers</span><span style="color: #0000ff">></span>
  11.   <span style="color: #0000ff"></</span><span style="color: #800000">entityFramework</span><span style="color: #0000ff">></span>

有System.Data.SQLite.EF6与System.Data.SqlClient，确实没有名称为System.Data.SQLite的提供程序。这里我一直不明白为什么sqlite会去找名称为System.Data.SQLite的提供程序，因为我们在连接串中配置的provider也是System.Data.SQLite.EF6。

那我们就在EF的配置节点中增加一个名为System.Data.SQLite的provider，但type仍然是System.Data.SQLite.EF6。最终的配置如图：

技术分享

红色部分是配置有变化的地方。

这里再运行程序就可以了。

 

注意：

1.连接串的配置。

 数据连接串可以指定绝对地址，也可以指定相对地址。像我的data source=SqliteTest.db，则SqliteTest.db要在Bin文件夹中，如果是web程序可以通过Data Source=|DataDirectory|\SqliteTest.db来配置在App_Data文件平中。

2.如果没有指定数据库中的表文件名，EF生成的SQL表都是用复数表示。就像我的程序中实体名是Person,但EF去查找的表名会是People。所以在数据库中定义的表名是People。

3.不支持CodeFirst模式，您需要自己先设计好Sqlite的表结构。

 

示例代码(packages文件太大，所以删除了)：SqliteLinqTest.zip

参考页面：http://qingqingquege.cnblogs.com/p/5933752.html

让EF飞一会儿:如何用Entity Framework 6 连接Sqlite数据库

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