http://www.web2py.com/books/default/chapter/29/06/the-database-abstraction-layer#Expressions
вторник, 25 мая 2021 г. в 22:36:47 UTC+3, valq...@gmail.com:
> db(...).update(some_field = db.some_table.some_field_or_another_field + 1)
> - should work ( it is a single db-query)
>
>
> вторник, 25 мая 2021 г. в 19:59:34 UTC+3, Rob Paire:
>
>> Hi All
>> Thank you for the helpful comments! I am fine leaving the SQL Execute
>> statement in place, but thought the question was worth asking.
>>
>> -Rob
>>
>> On Tuesday, May 25, 2021 at 8:06:46 AM UTC-4 Carlos Correia wrote:
>>
>>> Às 18:20 de 20/05/21, Rob Paire escreveu:
>>>
>>> Hello all,
>>>
>>> I am wondering if it's possible to use DAL update method to increment
>>> the value of table column H_REVNO in one line of code, and one trip to the
>>> database?
>>>
>>> I tried this query, and a couple of similar variations, but could not
>>> get it to work.
>>> db(db.KICKER.id == request.vars.kicker_id).update(H_REVNO=H_REVNO+1)
>>>
>>> Here is what I am using for now
>>> db.executesql("update KICKER set H_REVNO = H_REVNO + 1 where ID = "+
>>> str(request.vars.kicker_id)) which of course works.
>>>
>>> Thank you all!
>>>
>>>
>>>
>>> Hi,
>>>
>>> Using DAL you have to read the record first in other to get the value to
>>> be incremented. But, if there are many users it might lead to corrupted
>>> values due to concurrency.
>>>
>>> As far as I know, the latest is the only sane approach to solve your
>>> problem.
>>>
>>>
>>> Carlos Correia
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