Here is how it is now .. 1) cond = db.mytable(id=someid) generates SELECT <all columns> FROM mytable WHERE (id = someid) LIMIT 1 OFFSET 0;
2) cond = db(db.mytable.id==someid).select(db.mytable.id,limitby=(0, 1)) generates SELECT <mycolumn> FROM mytable WHERE (id = someid) ORDER BY pk LIMIT 1 OFFSET 0; What I would like to have is SELECT <mycolumn> FROM mytable WHERE (id = someid) LIMIT 1 ; On Wednesday, January 22, 2014 5:36:00 PM UTC+5:30, Jayadevan M wrote: > > Sorry. It works (I got something wrong earlier) but the limit has gone > away. I just have to ensure that there is ay least one record. > > > On Wed, Jan 22, 2014 at 5:28 PM, Jayadevan M > <maymala.jayade...@gmail.com>wrote: > >> I tried that. I get the error - >> <type 'exceptions.AttributeError'> 'Row' object has no attribute 'select' >> By the way, the "=" works. Additional information, this function is >> under modules. Do I have to imprt something to make the select construct >> work? >> >> >> On Wed, Jan 22, 2014 at 5:22 PM, Johann Spies <johann.sp...@gmail.com>wrote: >> >>> Oops. That should be >>> cond = db(db.mytable.id==someid).select(db.mytable.id) >>> >>> >>> On 22 January 2014 13:50, Johann Spies <johann.sp...@gmail.com> wrote: >>> >>>> cond = db.mytable(id=someid).select(db.mytable.id) >>>> >>>> Regards >>>> Johann >>>> >>>> >>>> On 22 January 2014 10:50, Jayadevan M <maymala.jayade...@gmail.com>wrote: >>>> >>>>> I am checking for existence of record in a table >>>>> >>>>> cond = db.mytable(id=someid) >>>>> if not cond : >>>>> do something >>>>> >>>>> This works fine. The query executed selects *all* columns and adds >>>>> LIMIT 1 OFFSET 0; The LIMIT and OFFSET are OK. Since I want to just check >>>>> for existence of a record, how can I rewrite this so that we have only >>>>> the >>>>> id column selected? I am trying to avoid a table scan and have just an >>>>> index scan. >>>>> >>>>> -- >>>>> 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 web2py+unsubscr...@googlegroups.com. >>>>> For more options, visit https://groups.google.com/groups/opt_out. >>>>> >>>> >>>> >>>> >>>> -- >>>> Because experiencing your loyal love is better than life itself, >>>> my lips will praise you. (Psalm 63:3) >>>> >>> >>> >>> >>> -- >>> Because experiencing your loyal love is better than life itself, >>> my lips will praise you. (Psalm 63:3) >>> >>> -- >>> 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 a topic in the >>> Google Groups "web2py-users" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/web2py/XYeLmZjQ6fY/unsubscribe. >>> To unsubscribe from this group and all its topics, send an email to >>> web2py+unsubscr...@googlegroups.com. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >> >> > -- 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 web2py+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
