select top 1 ClassId,ChannelId,ParentID,ClassName from Mir_Class where ClassId=8 order by ClassId asc,Access执行SQL查询返回DataTable
System.Data.SqlClient.SqlException: 在向服务器发送请求时发生传输级错误。 (provider: TCP 提供程序, error: 0 - 远程主机强迫关闭了一个现有的连接。)
   在 System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)
   在 System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
   在 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
   在 System.Data.SqlClient.TdsParserStateObject.WriteSni()
   在 System.Data.SqlClient.TdsParserStateObject.WritePacket(Byte flushMode)
   在 System.Data.SqlClient.TdsParserStateObject.ExecuteFlush()
   在 System.Data.SqlClient.TdsParser.TdsExecuteSQLBatch(String text, Int32 timeout, SqlNotificationRequest notificationRequest, TdsParserStateObject stateObj)
   在 System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async)
   在 System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result)
   在 System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method)
   在 System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method)
   在 System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
   在 System.Data.Common.DbCommand.System.Data.IDbCommand.ExecuteReader(CommandBehavior behavior)
   在 System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior)
   在 System.Data.Common.DbDataAdapter.Fill(DataTable[] dataTables, Int32 startRecord, Int32 maxRecords, IDbCommand command, CommandBehavior behavior)
   在 System.Data.Common.DbDataAdapter.Fill(DataTDataAccess打开数据库连接Error
System.Data.SqlClient.SqlException: 在与 SQL Server 建立连接时出现与网络相关的或特定于实例的错误。未找到或无法访问服务器。请验证实例名称是否正确并且 SQL Server 已配置为允许远程连接。 (provider: 命名管道提供程序, error: 40 - 无法打开到 SQL Server 的连接)
   在 System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
   在 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
   在 System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, SqlConnection owningObject, Boolean withFailover)
   在 System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject, Boolean withFailover)
   在 System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart)
   在 System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance)
   在 System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance)
   在 System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection)
   在 System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options)
   在 System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject)
   在 System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject)
   在 System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject)
   在 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
   在 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactselect top 1 ClassId,ChannelId,ParentID from Mir_Class where ParentID=8,Access执行SQL查询返回DataTable
System.InvalidOperationException: 超时时间已到。超时时间已到，但是尚未从池中获取连接。出现这种情况可能是因为所有池连接均在使用，并且达到了最大池大小。
   在 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
   在 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)
   在 System.Data.SqlClient.SqlConnection.Open()
   在 System.Data.Common.DbDataAdapter.QuietOpen(IDbConnection connection, ConnectionState& originalState)
   在 System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior)
   在 System.Data.Common.DbDataAdapter.Fill(DataTable[] dataTables, Int32 startRecord, Int32 maxRecords, IDbCommand command, CommandBehavior behavior)
   在 System.Data.Common.DbDataAdapter.DataAccess打开数据库连接Error
System.Data.SqlClient.SqlException: 在与 SQL Server 建立连接时出现与网络相关的或特定于实例的错误。未找到或无法访问服务器。请验证实例名称是否正确并且 SQL Server 已配置为允许远程连接。 (provider: 命名管道提供程序, error: 40 - 无法打开到 SQL Server 的连接)
   在 System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
   在 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
   在 System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, SqlConnection owningObject, Boolean withFailover)
   在 System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject, Boolean withFailover)
   在 System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart)
   在 System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance)
   在 System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance)
   在 System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection)
   在 System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options)
   在 System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject)
   在 System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject)
   在 System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject)
   在 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
   在 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactDataAccess打开数据库连接Error
System.Data.SqlClient.SqlException: 在与 SQL Server 建立连接时出现与网络相关的或特定于实例的错误。未找到或无法访问服务器。请验证实例名称是否正确并且 SQL Server 已配置为允许远程连接。 (provider: 命名管道提供程序, error: 40 - 无法打开到 SQL Server 的连接)
   在 System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject)
   在 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
   在 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)
   在