Subject RE: [firebird-support] read the next record of the table
Author Mercea Paul
Hi Fidel

At first look you can thing that every time you update the entire table, but
for each row you execute a select !



[] On Behalf Of Fidel Viegas
Sent: 13 June 2008 14:10
Subject: Re: [firebird-support] read the next record of the table

On Fri, Jun 13, 2008 at 12:03 PM, Svein Erling Tysvær
<> > wrote:
> What you do should work. The one thing I would expect to cause this to
> is if you didn't commit the transaction. Another things that could be of
> influence, is the field type of row_id, if it is an integer, decimal or
> (provided dialect 3) field, I cannot see how this could fail. Floating
> numbers is something completely different, they're approximate (may be
> 1.00000000232 when you think it is just 1) and shouldn't be used with
> comparison for equality. Of course, if field_a and field_b is incompatible
> field types, then you would also get trouble, but that would normally be
> very visible for you when you try to prepare the statement.

Hi Set,

From what I can see in the statement, that will update every single
row, because there is no filter condition in the update statement

if you do "update table set col = xxx", this will change every single
row in the table. The subselect is correct, but that is a condition
missing in the udpate statement, which I haven't figured out what it
is. Here is how it should be:

UPDATE myTable m
SET m.field_b =
SELECT m2.field_a
from myTable m2
where m2.row_id = m.row_id + 1
) where <condition>;

I haven't really figured what the <condition> is, but would like to
know if someone comes up with the solution to this.


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