SqlConnection 无法打开连接

Question

我有什么

http://www.freesqldatabase.com
一个数据库（DB_DATABASE var 在我的 asp.net 应用程序中）
数据库的用户名和密码 (DB_USER, DB_PASS)
主机URL (sql4.freesqldatabase.com [DB_SERVER])
一个目录，加三个表(DB_CATALOG)
一个端口(DB_PORT)

我的目标

从我的 asp.net 应用连接到我的数据库。

我尝试了什么

我尝试构建一个 SqlConnection，就像：

SqlConnection con = new SqlConnection(@"Data Source=(" + DB_SERVER + "\" + DB_DATABASE + "," + DB_PORT + ");Initial Catalog=" + DB_CATALOG + ";UID=" + DB_USER + ";PWD=" + DB_PASS + ";");

我已经使用 DB_DATABASE 作为实例名称，但我不确定（任何解释来澄清我的混乱将不胜感激！）

但我也试过没有它:

SqlConnection con = new SqlConnection(@"Data Source=(" + DB_SERVER + "," + DB_PORT + ");Initial Catalog=" + DB_CATALOG + ";UID=" + DB_USER + ";PWD=" + DB_PASS + ";");

除了这些之外还有几个选项，试图修改连接字符串，但还没有人工作=（

我得到了什么

好吧，当我试图打开连接时，我遇到了以下异常（我试图在这里寻找任何有用的数据，但我还不习惯这个...） :

   en System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   en System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   en System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, Boolean withFailover)
   en System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, Boolean withFailover)
   en System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString connectionOptions, SqlCredential credential, TimeoutTimer timeout)
   en System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout, SqlConnectionString connectionOptions, SqlCredential credential, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance)
   en System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData)
   en System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   en System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
   en System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   en System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   en System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   en System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   en System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   en System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   en System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   en System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
   en System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   en System.Data.SqlClient.SqlConnection.Open()
   en Gallery.Gallery.registerNewUser(String username, String encripted_password)

另外，发现

在 http://www.freesqldatabase.com/category/net/ ，他们说他们说：

Due to a bug within some MySQL connectors, the ‘Out of sync with server’ error is returned.

To resolve this, use a different version of the MySQL connector.

但是由于我在异常堆栈跟踪中没有看到任何相关信息，我不确定我是否受到此影响（加上它是 2011 年的新闻）。

我是不是在建立连接的时候做错了什么？我该如何解决？

提前致谢！

Answer 1

所有以"Sql"开头的对象，如"SqlConnection"、"SqlCommand"等，都是为SQL服务器制作的。显然你正在使用 MySQL 所以你需要一个不同的提供者：https://dev.mysql.com/downloads/connector/net/

将此提供程序添加为项目中的引用后，您将能够使用 "MySqlConnection"、"MySqlCommand" 等

SqlConnection 无法打开连接

SqlConnection not being able to open the connection

c#

asp.net

database-connection

freesqldatabase

我有什么

我的目标

我尝试了什么

我得到了什么

另外，发现