id |  name |  fav
1  |  abc  |  11,2,3,4,5,11,2
2  |
3  |
.
.
.

select id, name, group_concat(distinct uf.favid order by uf.id) as favs
from table t join
     UserFav uf
     on t.id = uf.userid
group by t.id;