这可能是 Windows 7 问题，但请致电
using (var context = new DataClassesDataContext())
{
if (!context.DatabaseExists())
{
context.CreateDatabase();
}
}
导致以下错误：
System.Data.SqlClient.SqlException 是 未处理的消息=数据库 'C:\Temp\SmallBusinessManager.mdf' 已经存在。选择不同的 数据库名称。 来源=.Net SqlClient 数据提供者错误代码=-2146232060 类别=16 行号=1 号码=1801 程序=“”
服务器=\.\pipe\952FCA9D-B4B6-4C sql\query 状态=3 堆栈跟踪： 在 System.Data.SqlClient.SqlConnection.OnError（SqlException 异常，布尔中断连接） 在 System.Data.SqlClient.SqlInternalConnection.OnError（SqlException 异常，布尔中断连接） 在 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning() 在 System.Data.SqlClient.TdsParser.Run（RunBehavior runBehavior、SqlCommand cmdHandler、 SqlDataReader数据流， 批量复制简单结果集 批量复制处理程序、TdsParserStateObject 状态对象) 在 System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds（字符串 方法名称，布尔异步） 在 System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery（DbAsyncResult 结果，字符串方法名称，布尔值 发送到管道） 在 System.Data.SqlClient.SqlCommand.ExecuteNonQuery() 在 System.Data.Linq.SqlClient.SqlProvider.ExecuteCommand（字符串 命令） 在 System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.CreateDatabase() 在 System.Data.Linq.DataContext.CreateDatabase()
但是我已经删除了数据库文件。 可能是什么原因造成的？ 文件真的存在但不知何故看不见吗？ 和路口有关系吗？
所以我也一直在尝试通过运行 DataContext.CreateDatabase() 命令创建一个基于文件的数据库（名为
C:\y jdatamig\IntermediateData.mdf）并得到相同的错误。
我使用的是带有 SQLExpress 2008 和 VS2008 的 Vista SP2，并按照 Josh 在他的回答中建议的那样使用了进程监视器。 这让我看到 SQL Server 正在写入其 error.log 文件，该文件又显示了以下相关信息块（此处提供了全部信息，以防其他人在消息中看到有用的信息）：
2010-06-23 17:04:10.50 Server SQL Server is starting at normal priority base (=7). This is an informational message only. No user action is required.
2010-06-23 17:04:10.50 Server Detected 2 CPUs. This is an informational message; no user action is required.
2010-06-23 17:04:10.55 Server Perfmon counters for resource governor pools and groups failed to initialize and are disabled.
2010-06-23 17:04:10.55 Server Using dynamic lock allocation. Initial allocation of 2500 Lock blocks and 5000 Lock Owner blocks per node. This is an informational message only. No user action is required.
2010-06-23 17:04:10.65 Server Node configuration: node 0: CPU mask: 0x00000003 Active CPU mask: 0x00000003. This message provides a description of the NUMA configuration for this computer. This is an informational message only. No user action is required.
2010-06-23 17:04:10.69 spid7s Starting up database 'master'.
2010-06-23 17:04:10.79 spid7s 1 transactions rolled forward in database 'master' (1). This is an informational message only. No user action is required.
2010-06-23 17:04:10.91 spid7s 0 transactions rolled back in database 'master' (1). This is an informational message only. No user action is required.
2010-06-23 17:04:10.91 spid7s Recovery is writing a checkpoint in database 'master' (1). This is an informational message only. No user action is required.
2010-06-23 17:04:11.12 spid7s Error: 5598, Severity: 16, State: 2.
2010-06-23 17:04:11.12 spid7s FILESTREAM feature is not supported on user instances.
2010-06-23 17:04:11.12 spid7s FILESTREAM: effective level = 0, configured level = 0, file system access share name = 'SQLEXPRESS'.
2010-06-23 17:04:11.25 spid7s SQL Trace ID 1 was started by login "sa".
2010-06-23 17:04:11.31 spid7s Starting up database 'mssqlsystemresource'.
2010-06-23 17:04:11.33 spid7s The resource database build version is 10.00.2531. This is an informational message only. No user action is required.
2010-06-23 17:04:11.90 spid9s Starting up database 'model'.
2010-06-23 17:04:11.91 Server Server local connection provider is ready to accept connection on [ \\.\pipe\95B6C915-3DB7-46\tsql\query ].
2010-06-23 17:04:11.94 Server Dedicated administrator connection support was not started because it is disabled on this edition of SQL Server. If you want to use a dedicated administrator connection, restart SQL Server using the trace flag 7806. This is an informational message only. No user action is required.
2010-06-23 17:04:11.95 spid7s Server name is 'JOHN-W500\95B6C915-3DB7-46'. This is an informational message only. No user action is required.
2010-06-23 17:04:12.22 spid7s Starting up database 'msdb'.
2010-06-23 17:04:12.27 Server The SQL Server Network Interface library could not register the Service Principal Name (SPN) for the SQL Server service. Error: 0x5, state: 4. Failure to register an SPN may cause integrated authentication to fall back to NTLM instead of Kerberos. This is an informational message. Further action is only required if Kerberos authentication is required by authentication policies.
2010-06-23 17:04:12.27 Server SQL Server is now ready for client connections. This is an informational message; no user action is required.
2010-06-23 17:04:12.60 spid9s Clearing tempdb database.
2010-06-23 17:04:15.49 spid9s Starting up database 'tempdb'.
2010-06-23 17:04:16.27 spid12s The Service Broker protocol transport is disabled or not configured.
2010-06-23 17:04:16.27 spid12s The Database Mirroring protocol transport is disabled or not configured.
2010-06-23 17:04:16.36 spid12s Service Broker manager has started.
2010-06-23 17:04:16.37 spid7s Recovery is complete. This is an informational message only. No user action is required.
2010-06-23 17:04:17.84 Logon Error: 15350, Severity: 16, State: 1.
2010-06-23 17:04:17.84 Logon An attempt to attach an auto-named database for file C:\y\bjdatamig\IntermediateData.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
2010-06-23 17:31:29.89 Logon Error: 15350, Severity: 16, State: 1.
2010-06-23 17:31:29.89 Logon An attempt to attach an auto-named database for file C:\y\bjdatamig\IntermediateData.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
2010-06-23 17:33:07.09 Logon Error: 15350, Severity: 16, State: 1.
2010-06-23 17:33:07.09 Logon An attempt to attach an auto-named database for file C:\y\bjdatamig\IntermediateData.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
2010-06-23 17:49:53.53 Logon Error: 15350, Severity: 16, State: 1.
2010-06-23 17:49:53.53 Logon An attempt to attach an auto-named database for file C:\y\bjdatamig\IntermediateData.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
2010-06-23 18:01:02.74 Logon Error: 15350, Severity: 16, State: 1.
2010-06-23 18:01:02.74 Logon An attempt to attach an auto-named database for file C:\y\bjdatamig\IntermediateData.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
2010-06-23 18:02:50.92 Logon Error: 15350, Severity: 16, State: 1.
2010-06-23 18:02:50.92 Logon An attempt to attach an auto-named database for file C:\y\bjdatamig\IntermediateData.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
2010-06-23 18:04:06.31 Logon Error: 15350, Severity: 16, State: 1.
2010-06-23 18:04:06.31 Logon An attempt to attach an auto-named database for file C:\y\bjdatamig\IntermediateData.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
2010-06-23 18:06:41.22 Logon Error: 15350, Severity: 16, State: 1.
2010-06-23 18:06:41.22 Logon An attempt to attach an auto-named database for file C:\y\bjdatamig\IntermediateData.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
我的 SQL 日志文件位于：
C:\Users\John\AppData\Local\Microsoft\Microsoft SQL Server Data\SQLEXPRESS\error.log
重要的是，对于我的情况，它表明用户实例不支持“功能”，似乎是关于流式传输文件，当然CreateDatabase正在尝试写入文件系统...
2010-06-23 17:04:11.12 spid7s Error: 5598, Severity: 16, State: 2.
2010-06-23 17:04:11.12 spid7s FILESTREAM feature is not supported on user instances.
...我的 APP.CONFIG 中的连接字符串指定了一个“用户实例”...
<add connectionString="Data Source=JOHN-W500\SQLEXPRESS;AttachDbFilename=C:\y\bjdatamig\IntermediateData.mdf;Integrated Security=True;User Instance=True" name="IntermediateData" providerName="System.Data.SqlClient" />
我更改了连接字符串
;Integrated Security=True;
到
;Integrated Security=False;
数据库已在文件系统上创建。
为什么我不必更改“用户实例”选项？嗯，我不确定。事实上，在我开始出现此错误之前，代码就可以工作，但我已经一个月没有尝试过 - 我的猜测可能是系统更新或 SQL Server 更改导致了它。 因此，尽管已解决，但它仍然有点神秘。
抓取Process Monitor，您将能够看到文件 io 操作以及它们失败的原因。我发现这通常是解决问题根源的最佳和最快的方法。这是一个很棒的实用程序。
您需要删除以下文件夹并重新启动计算机才能删除旧的用户实例。如果出现错误，声称文件正在使用中，您可以通过 Process Explorer“关闭处理”它们。
对于XP：
C:\Documents and Settings\username\Local Settings\Application Data\Microsoft\Microsoft SQL Server Data\SQLEXPRESS
对于 Vista：
C:\Users\username\AppData\Local\Microsoft\Microsoft SQL Server Data\SQLEXPRESS
有关用户实例的技术详细信息，请阅读标题为“SQL Server 2005 Express Edition 用户实例”的文章。