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
>
>
