Melvin Davidson <melvin6925@xxxxxxxxx> writes:
> On Sun, Dec 18, 2016 at 6:08 PM, John R Pierce <pierce@xxxxxxxxxxxx> wrote:
>> On 12/18/2016 2:52 PM, Jong-won Choi wrote:
>>> I have a NULL-able JSONB type column and want to perform upsert,
>>> concatenating with the existing value.
>> NULL does not mean 'NO' value in SQL it means UNKNOWN value. sort of like
>> the 'indeterminate' in math.
> Have you tried using CASE?
> INSERT INTO Fan (oid, campaigns, facts) VALUES (189,'{"campaign-id":
> "12345"}','{"attended": false}')
> ON CONFLICT (oid)
> DO UPDATE SET campaigns = EXCLUDED.campaigns,
> CASE WHEN fan.facts is NULL
> THEN facts = EXCLUDED.facts
> ELSE facts = fan.facts || EXCLUDED.facts
> END
> RETURNING *;
Another option is COALESCE:
...
DO UPDATE SET campaigns = EXCLUDED.campaigns,
facts = COALESCE(fan.facts, '{}'::jsonb) || EXCLUDED.facts
...
I'd argue though that if you think this is okay, then you're abusing
NULL; that's supposed to mean "unknown", not "known to be empty".
It would be better to initialize the column to '{}' to begin with.
regards, tom lane
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