使用动态生成的连接字符串使用实体框架连接到多个数据库源？

Question

使用实体框架连接数据库。

根据UI中的用户选择动态生成连接字符串。

场景是用户从UI中选择一些连接并基于该选择实体框架必须连接数据库查询。

以下代码用于生成实体连接字符串。但它没有按原样运作。

用于传递连接字符串的实体部分类。

public partial class Entities
{
   public Entities(string connectionName)
      : base(connectionName)
    {
    }
}

public static void GenerateEntityConnectionString(string serverName, string databaseName, string providerName,
      string databaseUserId, string databasePassword, short? databaseTimeout)
{
   string connnectionString = string.Empty;
   // Specify the provider name, server and database.
   //string providerName = "System.Data.SqlClient";
   //string serverName = ".";
   //string databaseName = "AdventureWorks";

   // Initialize the connection string builder for the
   // underlying provider.
   SqlConnectionStringBuilder sqlBuilder =
            new SqlConnectionStringBuilder();

   // Set the properties for the data source.
   sqlBuilder.DataSource = serverName;
   sqlBuilder.InitialCatalog = databaseName;
   sqlBuilder.IntegratedSecurity = false;
   sqlBuilder.UserID = databaseUserId;
   sqlBuilder.Password = databasePassword;
   sqlBuilder.MultipleActiveResultSets = true;
   sqlBuilder.ConnectTimeout = Convert.ToInt32(databaseTimeout);

   // Build the SqlConnection connection string.
   string providerString = sqlBuilder.ToString();

   // Initialize the EntityConnectionStringBuilder.
   EntityConnectionStringBuilder entityBuilder =
            new EntityConnectionStringBuilder();

   //Set the provider name.
   entityBuilder.Provider = providerName;

   // Set the provider-specific connection string.
   entityBuilder.ProviderConnectionString = providerString;

   // Set the Metadata location.
   entityBuilder.Metadata  = @"res://*/EF.EntitiesModal.csdl|res://*/EF.EntitiesModal.ssdl|res://*/EF.EntitiesModal.msl";
   //entityBuilder.Metadata = @"res://*/";
   connnectionString = entityBuilder.ConnectionString;

   ConnectionString = connnectionString;
}

更新 在使用动态生成的连接字符串时，实体框架会生成错误，即无效的对象名称。虽然表存在于数据库中。

查看下面的图片以便更好地理解。

表格下面有检查图片：

  

at System.Data.SqlClient.SqlConnection.OnError（SqlException   exception，Boolean breakConnection，Action 1 wrapCloseInAction) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action 1 wrapCloseInAction）at   System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning（TdsParserStateObject   stateObj，Boolean callerHasConnectionLock，Boolean asyncClose）at   System.Data.SqlClient.TdsParser.TryRun（RunBehavior runBehavior，   SqlCommand cmdHandler，SqlDataReader dataStream，   BulkCopySimpleResultSet bulkCopyHandler，TdsParserStateObject   stateObj，布尔＆amp; dataReady）at   System.Data.SqlClient.SqlDataReader.TryConsumeMetaData（）at   System.Data.SqlClient.SqlDataReader.get_MetaData（）at   System.Data.SqlClient.SqlCommand.FinishExecuteReader（SqlDataReader ds，   RunBehavior runBehavior，String resetOptionsString）at   System.Data.SqlClient.SqlCommand.RunExecuteReaderTds（的CommandBehavior   cmdBehavior，RunBehavior runBehavior，Boolean returnStream，Boolean   async，Int32超时，任务＆amp; task，Boolean asyncWrite，SqlDataReader   ds，Boolean describeParameterEncryptionRequest）at   System.Data.SqlClient.SqlCommand.RunExecuteReader（的CommandBehavior   cmdBehavior，RunBehavior runBehavior，Boolean returnStream，String   方法，TaskCompletionSource 1 completion, Int32 timeout, Task& task, Boolean asyncWrite) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) at System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) at System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior)
at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<Reader>b__c(DbCommand t, DbCommandInterceptionContext 1 c）at   System.Data.Entity.Infrastructure.Interception.InternalDispatcher 1.Dispatch[TTarget,TInterceptionContext,TResult](TTarget target, Func 3操作，TInterceptionContext interceptionContext，   行动3 executing, Action 3已执行）   System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.Reader（的DbCommand   命令，DbCommandInterceptionContext interceptionContext）at   System.Data.Entity.Internal.InterceptableDbCommand.ExecuteDbDataReader（的CommandBehavior   行为）   System.Data.Common.DbCommand.ExecuteReader（CommandBehavior behavior）
  在   System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands（EntityCommand   entityCommand，CommandBehavior行为）