这段时间写Android和IOS服务时 sql数据库查询有数据正常，没数据总是报异常：System.Data.SqlClient.SqlException (0x80131904): Timeout 时间已到。在操作完成之前超时时间已过或服务器未响应。 ---> System.ComponentModel.Win32Exception (0x80004005): 等待的操作过时。
   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放到数据库执行在1秒以内 到服务端就会超时。做了个时间测试，数据库执行确实用了30秒，然后就超时了。

找了很多方案，最后在数据库执行一下命令就好了：

exec sp_updatestats;