EF 多数据库切换配置(MSSQL/MySql)

 <?xml version="1.0" encoding="utf-8"?>
 <!--
   有关如何配置 ASP.NET 应用程序的详细信息，请访问
   https://go.microsoft.com/fwlink/?LinkId=301880
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 <configuration>
   <configSections>
     <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
     <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
   </configSections>
   <connectionStrings>
     <add name="DataModel" providerName="MySql.Data.MySqlClient" connectionString="Data Source=localhost;Initial Catalog=Demo;User ID=root;Password=123456" />
     <!--<add name="DataModel" connectionString="data source=.;initial catalog=Demo;persist security info=True;user id=sa;password=123456;multipleactiveresultsets=True;application name=EntityFramework" providerName="System.Data.SqlClient" />-->
   </connectionStrings>
   <appSettings>
     <add key="webpages:Version" value="3.0.0.0" />
     <add key="webpages:Enabled" value="false" />
     <add key="ClientValidationEnabled" value="true" />
     <add key="UnobtrusiveJavaScriptEnabled" value="true" />
   </appSettings>
   <system.web>
     <compilation debug="true" targetFramework="4.7.2" />
     <httpRuntime targetFramework="4.7.2" />
   </system.web>
   <runtime>
     <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
       <dependentAssembly>
         <assemblyIdentity name="Antlr3.Runtime" publicKeyToken="eb42632606e9261f" />
         <bindingRedirect oldVersion="0.0.0.0-3.5.0.2" newVersion="3.5.0.2" />
       </dependentAssembly>
       <dependentAssembly>
         <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" />
         <bindingRedirect oldVersion="0.0.0.0-11.0.0.0" newVersion="11.0.0.0" />
       </dependentAssembly>
       <dependentAssembly>
         <assemblyIdentity name="System.Web.Optimization" publicKeyToken="31bf3856ad364e35" />
         <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="1.1.0.0" />
       </dependentAssembly>
       <dependentAssembly>
         <assemblyIdentity name="WebGrease" publicKeyToken="31bf3856ad364e35" />
         <bindingRedirect oldVersion="0.0.0.0-1.6.5135.21930" newVersion="1.6.5135.21930" />
       </dependentAssembly>
       <dependentAssembly>
         <assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
         <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
       </dependentAssembly>
       <dependentAssembly>
         <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
         <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
       </dependentAssembly>
       <dependentAssembly>
         <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
         <bindingRedirect oldVersion="1.0.0.0-5.2.7.0" newVersion="5.2.7.0" />
       </dependentAssembly>
     </assemblyBinding>
   </runtime>
   <system.codedom>
     <compilers>
       <compiler language="c#;cs;csharp" extension=".cs" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="" compilerOptions="/langversion:default /nowarn:1659;1699;1701" />
       <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="" compilerOptions="/langversion:default /nowarn:41008 /define:_MYTYPE=\&quot;Web\&quot; /optionInfer+" />
     </compilers>
   </system.codedom>

   <entityFramework>
     <!--MySQL启用下面一段配置项-->
     <!--<defaultConnectionFactory type="MySql.Data.Entity.MySqlConnectionFactory, MySql.Data.Entity.EF6">
       <parameters>
         <parameter value="v11.0" />
       </parameters>
     </defaultConnectionFactory>-->
     <!--SQL SERVER 启用下面一行-->
     <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework" >
       <parameters>
         <parameter value="mssqllocaldb" />
       </parameters>
     </defaultConnectionFactory>
     <providers>
       <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
       <provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6, Version=6.10.9.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d">
       </provider>
     </providers>
   </entityFramework>

   <system.data>
     <DbProviderFactories>
       <remove invariant="MySql.Data.MySqlClient" />
       <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.10.9.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
     </DbProviderFactories>
   </system.data>

 </configuration>

DBContext配置：

this.SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());

或者

DBContext.cs

[DbConfigurationType(typeof(MySql.Data.Entity.MySqlEFConfiguration))]