代码第一个实体框架确实无法连接到数据库

Question

我知道这个问题必须先回答，但我找不到解决方案，我的情况。 我在Visual Studio 2013中创建了一个基于服务的数据库，并且我想连接到这个数据库。 我创建了dbSet，从的DbContext类heritating并添加entitiframework参考一切都很好，除了ConnectionString的

<connectionStrings> 
<add name ="master" connectionString="Data Source=(localdb)\v11.0; 
         AttachDbFilename=c:\users\reda\documents\visual studio 2013\Projects\Testing new things\Testing new things\master.mdf; 
         Integrated Security=True;"/> </connectionStrings> 

当我运行我的程序，我收到了Data.Entity.Core.ProviderIncompatibleException例外;这意味着它无法访问数据库，我在哪里错了？

btw，是否有任何其他解决方案来处理本地数据库？

的错误信息是：

Unhandled Exception: System.Data.Entity.Core.ProviderIncompatibleException: An e 
rror occurred accessing the database. This usually means that the connection to 
the database failed. Check that the connection string is correct and that the ap 
propriate DbContext constructor is being used to specify it or find it in the ap 
plication's config file. See http://go.microsoft.com/fwlink/?LinkId=386386 for i 
nformation on DbContext and connections. See the inner exception for details of 
the failure. ---> System.Data.Entity.Core.ProviderIncompatibleException: The pro 
vider did not return a ProviderManifestToken string. ---> System.Data.SqlClient. 
SqlException: A network-related or instance-specific error occurred while establ 
ishing a connection to SQL Server. The server was not found or was not accessibl 
e. Verify that the instance name is correct and that SQL Server is configured to 
allow remote connections. (provider: SQL Network Interfaces, error: 50 - Local 
Database Runtime error occurred. The specified LocalDB instance does not exist. 
) 
    at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception 
, Boolean breakConnection, Action`1 wrapCloseInAction) 
    at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObj 
ect stateObj, Boolean callerHasConnectionLock, Boolean asyncClose) 
    at System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternal 
ConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Bool 
ean encrypt, Boolean trustServerCert, Boolean integratedSecurity, Boolean withFa 
ilover) 
    at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo 
serverInfo, String newPassword, SecureString newSecurePassword, Boolean ignoreSn 
iOpenTimeout, TimeoutTimer timeout, Boolean withFailover) 
    at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo 
serverInfo, String newPassword, SecureString newSecurePassword, Boolean redirect 
edUserInstance, SqlConnectionString connectionOptions, SqlCredential credential, 
TimeoutTimer timeout) 
    at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTime 
r timeout, SqlConnectionString connectionOptions, SqlCredential credential, Stri 
ng newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance) 
    at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdent 
ity identity, SqlConnectionString connectionOptions, SqlCredential credential, O 
bject providerInfo, String newPassword, SecureString newSecurePassword, Boolean 
redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData r 
econnectSessionData) 
    at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOp 
tions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConn 
ectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions) 

    at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConn 
ectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConne 
ctionPoolKey poolKey, DbConnectionOptions userOptions) 
    at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owning 
Object, DbConnectionOptions userOptions, DbConnectionInternal oldConnection) 
    at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection o 
wningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection 
) 
    at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection ow 
ningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean o 
nlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& co 
nnection) 
    at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection ow 
ningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbCon 
nectionInternal& connection) 
    at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection 
owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions 
, DbConnectionInternal oldConnection, DbConnectionInternal& connection) 
    at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(Db 
Connection outerConnection, DbConnectionFactory connectionFactory, TaskCompletio 
nSource`1 retry, DbConnectionOptions userOptions) 
    at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection 
outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 
retry, DbConnectionOptions userOptions) 
    at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 re 
try) 
    at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry) 
    at System.Data.SqlClient.SqlConnection.Open() 
    at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.<Ope 
n>b__38(DbConnection t, DbConnectionInterceptionContext c) 
    at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispat 
ch[TTarget,TInterceptionContext](TTarget target, Action`2 operation, TIntercepti 
onContext interceptionContext, Action`3 executing, Action`3 executed) 
    at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.Open 
(DbConnection connection, DbInterceptionContext interceptionContext) 
    at System.Data.Entity.SqlServer.SqlProviderServices.<>c__DisplayClass31.<Usin 
gConnection>b__2f() 
    at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.<>c__DisplayClass 
1.<Execute>b__0() 
    at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](
Func`1 operation) 
    at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action op 
eration) 
    at System.Data.Entity.SqlServer.SqlProviderServices.UsingConnection(DbConnect 
ion sqlConnection, Action`1 act) 
    at System.Data.Entity.SqlServer.SqlProviderServices.UsingMasterConnection(DbC 
onnection sqlConnection, Action`1 act) 
    at System.Data.Entity.SqlServer.SqlProviderServices.GetDbProviderManifestToke 
n(DbConnection connection) 
    at System.Data.Entity.Core.Common.DbProviderServices.GetProviderManifestToken 
(DbConnection connection) 
    --- End of inner exception stack trace --- 
    at System.Data.Entity.Core.Common.DbProviderServices.GetProviderManifestToken 
(DbConnection connection) 
    at System.Data.Entity.Utilities.DbProviderServicesExtensions.GetProviderManif 
estTokenChecked(DbProviderServices providerServices, DbConnection connection) 
    --- End of inner exception stack trace --- 
    at System.Data.Entity.Utilities.DbProviderServicesExtensions.GetProviderManif 
estTokenChecked(DbProviderServices providerServices, DbConnection connection) 
    at System.Data.Entity.Infrastructure.DefaultManifestTokenResolver.<>c__Displa 
yClass1.<ResolveManifestToken>b__0(Tuple`3 k) 
    at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Fu 
nc`2 valueFactory) 
    at System.Data.Entity.Infrastructure.DefaultManifestTokenResolver.ResolveMani 
festToken(DbConnection connection) 
    at System.Data.Entity.Utilities.DbConnectionExtensions.GetProviderInfo(DbConn 
ection connection, DbProviderManifest& providerManifest) 
    at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection) 
    at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalCo 
ntext internalContext) 
    at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input) 
    at System.Data.Entity.Internal.LazyInternalContext.InitializeContext() 
    at System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType 
(Type entityType) 
    at System.Data.Entity.Internal.Linq.InternalSet`1.Initialize() 
    at System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext() 
    at System.Data.Entity.Internal.Linq.InternalSet`1.ActOnSet(Action action, Ent 
ityState newState, Object entity, String methodName) 
    at System.Data.Entity.Internal.Linq.InternalSet`1.Add(Object entity) 
    at System.Data.Entity.DbSet`1.Add(TEntity entity) 
    at Testing_new_things.Program.Main(String[] args) in c:\Users\Reda\Documents\ 
Visual Studio 2013\Projects\Testing new things\Testing new things\Program.cs:lin 
e 19 
Press any key to continue . . . 

Answer 1

连接字符串缺少提供商的信息。将其更改为实际的连接字符串太在这

<add name ="master" connectionString="Data Source=(localdb)\v11.0; 
        AttachDbFilename=c:\users\reda\documents\visual studio 2013\Projects\Testing new things\Testing new things\master.mdf; 
        Integrated Security=True;" 
providerName="System.Data.SqlClient"/>