Need SQL Query to find Parent records without child records

Question

I am not at all conversant in SQL so was hoping someone could help me with a query that will find all the records in a parent table for which there are no records in a child

Answer 1

With another example as

Enumerate table

    id: SERIAL
    name: TEXT
    enumerate_id: INT

All parents who have children (all branches of a tree, even roots, but no leaf!)

SELECT id, name, enumerate_id
FROM enumerate p
WHERE EXISTS (
    SELECT 1 FROM enumerate c
    WHERE c.enumerate_id = p.id
);

All children who don't have children (all leafs of a tree)

SELECT id, name, enumerate_id
FROM enumerate p
WHERE NOT EXISTS (
    SELECT 1 FROM enumerate c
    WHERE c.enumerate_id = p.id
);

Note that the only one who changes is the NOT EXISTS

Hope it helps