I have mySql statement by using a sub query. However, I want the statement to be a nested query?

1.

select sname

from S

where s_num in

(select s_num

from SPJ

Where j_num = 'j2');

2.

select sname

from S

where s_num in

(select s_num

from J,SPJ

where J.j_num = SPJ.j_num

and city = 'Athens');

3.

select pname

from P

where p_num not in

(select p_num

from SPJ

where j_num = 'j3');