Finally Here is what i found after an hr of digging web2py group:
fmax=db.table.field.max(),
fmin=db.table.field.min()
fcount=db.table.field.count()
fsum=db.table.field.sum())
rows = db(query).select(fmax,fmin,fcount,fsum)
vmax=rows[0][fmax]
vmin=rows[0][fmin]
vavg=rows[0][fsum]/(rows[0][fcount] or 1)
does not work on GAE
On 6/5/11, Phyo Arkar <phyo.arkarl...@gmail.com> wrote:
> I am also needing to find out max value of a field , seems like it is
> undocumented.
>
> Is it exist? Where in api doc should i look for.
>
> On 4/4/11, Anthony <abasta...@gmail.com> wrote:
>> On Monday, April 4, 2011 9:39:31 AM UTC-4, Neveen Adel wrote:
>>>
>>> Thanks a lot Massimo :)
>>>
>>> The problem with this solution is that i have a table has member_id as
>>> foreign key and by this solution that data will be lost.
>>
>>
>> Are you saying in the legacy database, the 'member' table has a
>> 'membership_id' field, which is an auto-increment integer field and is
>> linked as a foreign key in one or more other tables? In that case, why
>> wouldn't Massimo's suggestion work? If you specify Field('membership_id',
>> type='id'), you are telling web2py not to create a field named 'id', but
>> instead to use the 'membership_id' field as the auto-incrementing primary
>> key for the 'member' table. I would think it would still work as a
>> foreign
>> key in other tables in that case. Have you tried it?
>>
>> Also, as an aside, if you need the MAX of a field, I believe the web2py
>> DAL
>> has a max() method (as well as min and sum), but it doesn't appear to be
>> documented in the book, and I'm not sure about the details of its usage.
>> Perhaps Massimo or someone else can elaborate (and maybe even update the
>> book).
>>
>> Anthony
>>
>>
>>
>>> On Apr 4, 3:31 pm, Massimo Di Pierro <massimo....@gmail.com>
>>> wrote:
>>> > how about
>>> >
>>> > db.define_table("member",
>>> > SQLField("membership_id", "id"),
>>> > SQLField("first_name", "string", notnull=True)
>>> > )
>>> >
>>> > and "membership_id" would be your "id" field?
>>> >
>>> > On Apr 4, 8:03 am, Neveen Adel <nevo...@gmail.com> wrote:
>>> >
>>> > > Thanks Anthony for your reply.
>>> >
>>> > > The table already have an old data so i can't remove the column id
>>> > > or
>>> > > change in the database structure.
>>> >
>>> > > Is there another solution in controller level not database level?
>>> >
>>> > > Thanks in Advance
>>> >
>>> > > On Apr 4, 2:54 pm, Anthony <abas...@gmail.com> wrote:
>>> >
>>> > > > Your table already includes an 'id' field by default, which is an
>>> > > > auto-increment integer field starting at 1. Why do you need a
>>> separate
>>> > > > 'membership_id' field? If it's a legacy database and you need the
>>> name of
>>> > > > the 'id' field to be 'membership_id', you can simply define the
>>> > > > field
>>> type
>>> > > > as 'id' (seehttp://
>>> web2py.com/book/default/chapter/06?search=auto-increment
>>> > > > ).
>>> >
>>> > > > Also, you should use Field() instead of SQLField() -- they're both
>>> the same,
>>> > > > but the latter has been deprecated in favor of the former.
>>> >
>>> > > > Anthony
>>> >
>>> > > > On Monday, April 4, 2011 8:35:00 AM UTC-4, Neveen Adel wrote:
>>> > > > > Hello,
>>> >
>>> > > > > I have the following table:
>>> >
>>> > > > > db.define_table("member",
>>> > > > > SQLField("membership_id", "integer",notnull=True),
>>> > > > > SQLField("first_name", "string", notnull=True)
>>> > > > > )
>>> >
>>> > > > > and i want the membership id to be incremented automatically.
>>> >
>>> > > > > the way i used :
>>> >
>>> > > > > every time i inserted it , i select the max membership_id and
>>> adding
>>> > > > > one on its value as:
>>> >
>>> > > > > result=db.executesql("select max(membership_id) from member")
>>> > > > > record=result[0]
>>> > > > > if record[0]:
>>> > > > > next_membership_id = record[0]+1
>>> > > > > else:
>>> > > > > next_membership_id=1
>>> > > > > form.vars.membership_id=next_membership_id
>>> >
>>> > > > > But this solution allows duplicates??
>>> >
>>> > > > > could anyone tell me what is the perfect solution?
>>> >
>>> > > > > Thanks in Advance
>>
>>
>
