Alex Brasetvik wrote:
> On 12/20/09 13:31 , Igor Katson wrote:
> 
>> I want to increment a column by 1 with
>>
>> UPDATE table SET column = column + 1 WHERE id = %(id)s,
> 
> This is covered here:
> http://www.sqlalchemy.org/docs/06/sqlexpression.html
> 
>> however, when writing "instance.column += 1" in python, it translates it to
>>
>> UPDATE table SET column = <OLD_VALUE> + 1
> 
> That's because instance.column returns the integer value. If you do
> "table.c.column + 1", however, that will return a _BinaryExpression.
> 
> So, what you want, is something like
> 
>     table.update(where_clause, dict(column=table.c.column + 1)
> 
> Hope this helps.
> 
Thanks, Alex, your variant seems really the same as mine. I have found a 
way to do that though simpler, this is:

instance.column = table.c.column + 1

Works like a charm, though instance.column becomes a binary expression 
and you can not access the real value until you do session.flush

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