create view foo as select session_id, start_session, end_session, user_id from bar;

##</code><code>##


SELECT DISTINCT foo.user_id AS user, 
foo.session_id  AS session1,
bar.session_id  AS session2,
foo.start_session AS start1,
bar_.start_session AS start2,
foo.end_session AS end1,
bar_.end_session AS end2 FROM foo,bar

WHERE foo.user_id != bar_.user_id 
AND bar_.start_session >= foo.start_session 
AND bar_.start_session <= foo.end_session 
AND foo.session_id != bar_.session_id 
order by start1 ASC;