sqlite> SELECT P1.name, P2.name
   ...> FROM person P1
   ...> JOIN friend F ON P1.id = F.person
   ...> JOIN person P2 ON F.friend = P2.id
   ...> WHERE P1.id IN (     
   ...>   SELECT F.friend
   ...>   FROM person P
   ...>   JOIN friend F ON P.id = F.person
   ...>   WHERE P.name = 'Bob'
   ...> ) ;
P1.name|P2.name
Al|Bob
Al|Chuck
Al|Frank
Al|Ibrahim
Doug|Bob
Doug|Chuck
Doug|Hamza
Gary|Bob
Gary|Hamza
Gary|Ibrahim