Postgresql column reference "id" is ambiguous

You need the table name/alias in the SELECT part (maybe (vg.id, name)) :

SELECT (vg.id, name) FROM v_groups vg 
inner join people2v_groups p2vg on vg.id = p2vg.v_group_id
where p2vg.people_id =0;

I suppose your p2vg table has also an id field , in that case , postgres cannot find if the id in the SELECT refers to vg or p2vg.

you should use SELECT(vg.id,vg.name) to remove ambiguity