Multiple `ON CONFLICT` in insert query - sql

Question

I have a table which have columns like id, name, start_date, end_date
and 2 unique constraints
unique(id, name, start_date)
and
unique(id, name, end_date)
now when I am writing insert query for this table, I have something like
insert into table (id, name, start_date, end_date)
values (1, 'test', 'example-start-date', 'example-end-date')
on conflict (id, name, start_date) set something
on conflict (id, name, end_date) set something
but getting errors, is this not allowed?
thanks

Answer 1

The answer depends on something.
For DO NOTHING, the answer is simply to use a single clause without specifying the columns:
ON CONFLICT DO NOTHING
That can deal with conflicts on multiple unique constraints.
For DO UPDATE, there is no straightforward solution. The syntax diagram in the documentation shows that you can only have a single ON CONFLICT clause that determines a single unique index.
You could use procedural code to do it in the old-fashioned way, for example in PL/pgSQL:
DECLARE
v_constraint text;
BEGIN
LOOP -- endless loop until INSERT or UPDATE succeeds
BEGIN
INSERT INTO ...;
EXIT; -- leave loop if INSERT succeeds
EXCEPTION
WHEN unique_violation THEN
GET STACKED DIAGNOSTICS v_constraint := CONSTRAINT_NAME;
END;
CASE v_constraint
WHEN 'constraint_name_1' THEN
UPDATE ...;
WHEN 'constraint_name_2' THEN
UPDATE ...;
END CASE;
EXIT WHEN FOUND; -- leave loop if UPDATE changed a row
END LOOP;
END;