应该是这么理解：
按照条件OWNER='Sunly' AND sex='f'分组，数据符合OWNER='Sunly' AND sex='f'有两条，不符合的有5条。

附：

1. USE `test`;
   
2. 
   
3. /*Table structure for table `pet` */
   
4. 
   
5. DROP TABLE IF EXISTS `pet`;
   
6. 
   
7. CREATE TABLE `pet` (
   
8.   `name` varchar(20) DEFAULT NULL,
   
9.   `owner` varchar(20) DEFAULT NULL,
   
10.   `species` varchar(20) DEFAULT NULL,
    
11.   `sex` char(1) DEFAULT NULL,
    
12.   `birth` datetime DEFAULT NULL,
    
13.   `death` datetime DEFAULT NULL
    
14. ) ENGINE=MyISAM DEFAULT CHARSET=utf8;
    
15. 
    
16. /*Data for the table `pet` */
    
17. 
    
18. insert  into `pet`(`name`,`owner`,`species`,`sex`,`birth`,`death`) values ('names','owners','cat','f','1993-02-03 00:00:00',NULL),('Hodl','Same','Hog','m',NULL,'1999-01-14 00:00:00'),('Hudla','Sunly','Hdd','f',NULL,NULL),('Fami','Same','cat','f',NULL,NULL),('Skkil','Hongk','dag','m',NULL,NULL),('Hfliy','Daoiing','Mices','f',NULL,NULL),('Hfl','Same','Mices','f',NULL,NULL);

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