upsert to table returning the id of last record upserted

Question

I have a very simple upsert I am trying to make work but unsuccessfully so far.

Consider the table:

CREATE TABLE bla(id TEXT PRIMARY KEY, data INT);

and the insert:

INSERT INTO bla(id, data) VALUES('12wed', 23) RETURNING (id);

And so far so good.

The logic I am trying to implement though is the following:

if no record with id=id: 
    insert and return id, 
else:
    do nothing

I tried

INSERT INTO bla(id, data) VALUES('12wed', 23) 
RETURNING (id) 
ON CONFLICT(id) DO NOTHING;

But I get the following error:

ERROR:  syntax error at or near "ON"
LINE 3: ON CONFLICT(id) DO NOTHING;

Answer 1

You made a mistake with the expression. The correct version:

INSERT INTO bla(id, data) VALUES('12wed', 23) 
ON CONFLICT(id) DO NOTHING
RETURNING (id);

It's exactly what you want:

hh=# INSERT INTO bla(id, data) VALUES('12wed', 23) ON CONFLICT(id) DO NOTHING RETURNING (id);
 id 
----
(0 rows)

INSERT 0 0

hh=# INSERT INTO bla(id, data) VALUES('12wed_new', 23) ON CONFLICT(id) DO NOTHING RETURNING (id);
   id   
--------
 12wed_new
(1 row)

INSERT 0 1