A query which returns a name and his/her friends, based on relId

Question

I'm new in sql. I got stuck into this problem, and I can't figure it out how can I solve this.

I've got 2 tables.

1. person: personId,name.
2. personRel: id,personId,relId(personId).

The problem is: How can I return with one query the person's name and the other's name, whom they knew.

Answer 1

You would use two joins:

select pr.*, p.name, ppr.name as rel_name
from personRel pr left join
     person p
     on p.personid = pr.personid left join
     person ppr
     on ppr.personid = pr.relid;