It depends a query is always field==value so you can do
query = db.table.field == value row = db(query).select(limitby=(0,10)).first() or row = db.table(query) (they are equivalent) But db.table(...) can take an "implicit query" db.table(fieldname=value) which is a more compact way to do db.table(db.table.field==value) The most common way to use db.table(...) is this db.table(id) or db.table(id, fieldname=value) # returns the record only of the fieldname==value or db.table(id, query) # returns the record only if the query is true. On Sunday, 20 November 2016 09:08:38 UTC-6, Meinolf wrote: > > Hi Massimo > > Just came across this post and got a bit alarmed, so when i check if a > record exists i don't have to use the usual '==' but instead '=' ? > > On Monday, October 10, 2011 at 3:55:27 PM UTC+2, Massimo Di Pierro wrote: >> >> row = db.postcode_cache(postcode=postcode) >> if not row: >> db.postcode_cache.insert(postcode=postcode,nearset=nearest) >> elif not row.nearest: row.update_record(nearset=nearest) >> else: pass # do nothing >> >> On Oct 10, 8:22 am, Chris Rowson <[email protected]> wrote: >> > Hi list, >> > >> > I have a database table which looks like this: >> > >> > postcode_cache >> > ------------------------ >> > postcode (UNIQUE) >> > lat >> > lon >> > nearest >> > >> > I want to test first whether or not a record exists for 'postcode' and >> > if a record does exist, I want to check whether the 'nearest' field >> > contains any data. >> > >> > I've tried this: >> > >> > if db(db.postcode_cache.postcode==postcode).select().first()==None: >> > create_a_new_postcode_record() >> > >> > elif >> db(db.postcode_cache.postcode==postcode).select(db.postcode_cache.nearest)= >> =None: >> > populate_the_nearest_field() >> > >> > else: >> > nothing_to_do() >> > >> > And while the check to establish whether or not a record exists seems >> > to work, the check to see whether or not the 'nearest' field within >> > the record is populated doesn't seem to work. >> > >> > Can anyone tell me what I'm doing wrong please? >> > >> > Thank you, >> > >> > Chris > > -- Resources: - http://web2py.com - http://web2py.com/book (Documentation) - http://github.com/web2py/web2py (Source code) - https://code.google.com/p/web2py/issues/list (Report Issues) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
