Question

由于this MSDN article about the AttachDbFileName property

，我期待这种行为

第一次使用此选项连接到数据库时连接字符串，SQL Server Express或LocalDB实例附加数据库，它保持附加。当你想连接到将来可以使用相同的数据库而不使用初始目录如果您愿意，可以使用AttachDbFileName。

我有一个Entity Framework使用的连接字符串：

<add name="DatabaseContext" providerName="System.Data.SqlClient" connectionString="Server=(localdb)\MSSQLLocalDB;Database=DatabaseName;Integrated Security=True;AttachDbFileName=|DatabaseName|\DatabaseName.mdf" />

在SQL Management Studio中打开数据库后，这个工作正常，为其提供AttachDbFileName值，并将绝对路径作为附加参数。

但是，如果我没有先将它与SQL Management Studio连接，那么当我尝试在数据库上运行EF迁移时，我会收到以下错误：

System.Data.SqlClient.SqlException (0x80131904): Cannot create file 'C:\Users\user\Desktop\folder\DatabaseName.mdf' because it already exists. Change the file path or the file name, and retry the operation.
CREATE DATABASE failed. Some file names listed could not be created. Check related errors.
   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, Boolean& dataReady)
   at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<NonQuery>b__0(DbCommand t, DbCommandInterceptionContext`1 c)
   at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TTarget,TInterceptionContext,TResult](TTarget target, Func`3 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed)
   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.NonQuery(DbCommand command, DbCommandInterceptionContext interceptionContext)
   at System.Data.Entity.SqlServer.SqlProviderServices.<>c__DisplayClass1a.<CreateDatabaseFromScript>b__19(DbConnection conn)
   at System.Data.Entity.SqlServer.SqlProviderServices.<>c__DisplayClass33.<UsingConnection>b__32()
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.<>c__DisplayClass1.<Execute>b__0()
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action operation)
   at System.Data.Entity.SqlServer.SqlProviderServices.UsingConnection(DbConnection sqlConnection, Action`1 act)
   at System.Data.Entity.SqlServer.SqlProviderServices.UsingMasterConnection(DbConnection sqlConnection, Action`1 act)
   at System.Data.Entity.SqlServer.SqlProviderServices.CreateDatabaseFromScript(Nullable`1 commandTimeout, DbConnection sqlConnection, String createDatabaseScript)
   at System.Data.Entity.SqlServer.SqlProviderServices.DbCreateDatabase(DbConnection connection, Nullable`1 commandTimeout, StoreItemCollection storeItemCollection)
   at System.Data.Entity.Core.Common.DbProviderServices.CreateDatabase(DbConnection connection, Nullable`1 commandTimeout, StoreItemCollection storeItemCollection)
   at System.Data.Entity.Core.Objects.ObjectContext.CreateDatabase()
   at System.Data.Entity.Migrations.Utilities.DatabaseCreator.Create(DbConnection connection)
   at System.Data.Entity.Migrations.DbMigrator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
   at System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration)
   at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update()

这看起来好像由于某种原因没有自动附加数据库，然后尝试创建它，好像文件不存在一样。

是否有其他连接字符串选项或LocalDB配置可以修复此问题，以便数据库自动附加到第一个连接上？

Answer 1

答案是微不足道的：.mdf和.ldf文件是在较新版本的SQL服务器中创建的，因此旧版本没有附加它们，就好像它们不存在一样。

LocalDB .mdf文件未在连接字符串中使用AttachDbFileName自动附加

1 个答案: