這段時間寫Android和IOS服務時 sql數據庫查詢有數據正常，沒數據總是報異常：System.Data.SqlClient.SqlException (0x80131904): Timeout 時間已到。在操作完成之前超時時間已過或服務器未響應。 ---> System.ComponentModel.Win32Exception (0x80004005): 等待的操作過時。
   在 System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   在 System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   在 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   在 System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   在 System.Data.SqlClient.SqlDataReader.TrySetMetaData(_SqlMetaDataSet metaData, Boolean moreInfo)
   在 System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   在 System.Data.SqlClient.SqlDataReader.TryConsumeMetaData()
   在 System.Data.SqlClient.SqlDataReader.get_MetaData()
   在 System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
   在 System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds)
   在 System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite)
   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.ExecuteReader(CommandBehavior behavior)
   在 AppServiceDAL.ClsSqlHelperDAL.fnExecuteReader(String _sConnectionString, CommandType _oCmdType, String _sCmdText, SqlParameter[] _oCommandParameters)
ClientConnectionId:bcab2341-64f4-4dae-92c4-6bfca904321b

但是把sql放到數據庫執行在1秒以內 到服務端就會超時。做了個時間測試，數據庫執行確實用了30秒，然后就超時了。

找了很多方案，最后在數據庫執行一下命令就好了：

exec sp_updatestats;