2016-06-02 14:23 GMT-03:00 Steve Crawford <scrawf...@pinpointresearch.com>:
> Something like: > > select max(id) from yourtable where sts=0 and ref_id is null; > > That assumes that ref_id is null. It would help to see your table > structure and the query you tried that doesn't work. If ref_id is actually > a character string then you might need ref_id='' or coalesce(ref_id,'')='' > if it can be null or empty string. > > Cheers, > Steve > > > On Thu, Jun 2, 2016 at 10:16 AM, Steve Clark <steve.cl...@netwolves.com> > wrote: > >> Hi List, >> >> I am a noob trying to do something that seems like it should be easy but >> I can't figure it out. >> >> I have a table like so: >> >> id | ref_id | sts >> ------------------ >> 1 | | 0 >> 2 | 1 | 1 >> 3 | | 0 >> 4 | | 0 >> 5 | 4 | 1 >> 6 | | 0 >> 7 | 6 | 1 >> >> I want to find the max(id) whose sts is 0 but whose id is not referenced >> by ref_id. >> >> so the answer would be id=3. >> >> Thanks for any pointers, >> Steve >> >> -- >> >> >> >> -- >> Sent via pgsql-general mailing list (pgsql-general@postgresql.org) >> To make changes to your subscription: >> http://www.postgresql.org/mailpref/pgsql-general >> > > I think sts=0 means ref_id is null So, what I think he wants to achieve is: select max(id) from yourtable where sts=0 and id not in (select ref_id from yourtable); Isn't it?
