On Mon, Jan 11, 2010 at 12:49 PM, Andy Shellam <andy-li...@networkmail.eu> wrote: > With the above in mind, I decided on the following check to enforce this: > > (state = 'Unconfirmed'::client.order_state AND invoice_id = NULL) OR (state > != 'Unconfirmed'::client.order_state AND invoice_id != NULL)
Nothing can = null. and invoice_id IS NULL is the proper nomenclature. Also, something <> NULL makes no sense, because we don't know what NULL is, so that becomes something IS NOT NULL Also != is not proper SQL, although many dbs understand it, <> is the proper way to write NOT EQUAL TO. > However PostgreSQL (8.4.2) converts this to the following: > > state = 'Unconfirmed'::client.order_state AND invoice_id = NULL::integer OR > state <> 'Unconfirmed'::client.order_state AND invoice_id <> NULL::integer ANDs have priority of ORs so the removal of the parenthesis makes no great change here. also, SQL standard is <> not !=. I'm guessing the real problems here are your NULL handling. See if changing it to IS NULL / IS NOT NULL gets you what you want. -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
