命名空间“System.Data”中不存在类型或命名空间名称“SqlServerCe”SqlCeConnectionsqlceConn=newSqlCeConnection("server=.;database=db_Stream;uid=sa;pwd=");sqlceConn.Open();SqlCeCommandsqlceCmd=newSqlCeCommand(sqlStr,sqlceConn);SqlCeDataReadersqlDr=sqlceCmd.ExecuteReader();sqlDr.Read(