关于下面代码段的说法错误的是( )。NSMutableArray *allStudents=[[NSMutableArray alloc]init];sql=@"select * from student";FMResultSet *resultSet=[db executeQuery:sql];while ([resultSet next]) { Student *stu=[[ Student alloc ] init]; stu.stuID=[resultSet stringForColumn:@"sID"]; stu.stuName=[resultSet stringForColumn:@"sName"]; stu.stuAge=[resultSet intForColumn:@"sAge"]; [allStudents addObject:stu];}