请尝试：

select city,sum(gender='f') as f_count,sum(gender='m') as m_count
from my_table
group by city;

结果：

city  f_count m_count
abc         1      1
def         0      1

Demo

数据库服务器：

select 
 city
,count(case when gender = 'm' then 1 else null end) as m_count
,count(case when gender <> 'm' then 1 else null end) as f_count
from table_name 
group by city

结果：

city  | f_count   | m_count
abc   |      1    |    1
def   |      0    |    1

select city, sum(male),sum(female) from
(select city ,count(gender) as male,0 as female from temp where gender='M' group by city 
union 
select city , 0,count(gender) as female from temp where gender='F'group by city)
group by city;