(SQL) group by

select * from database
where gender = 'female'
group by age

/* Example output: */
/* The youngest female is 16, the oldest 20 years old */
16
17
18
19
20

select *, count(*) from database
where gender = 'female'
group by age

/* Example output: */
/* The youngest female is 16, the oldest 20 years old */
/* The females' ages have a gaussian distribution     */
16 12 
17 25
18 50 
19 25
20 12