Morning Tim,

>> The only trouble is that:
>> update mytable set total=total+10.12,
>> databasename='Firebird' where mykey=10
>>
>> updates all fields except total. And the whole thing works
>> most of the time. I think this would suggest the triggers are fine.

Not necessarily. It is possible that, under certain circumstances, the
trigger can prevent updates to the total column.


However, there is an even simpler reason why the updates are not
happening:

SQL> create table funny(id integer, my_value decimal(10,2));
SQL> commit;

SQL> insert into funny (id, my_value) values (10, null);
SQL> insert into funny (id, my_value) values (20, 20.2);
SQL> commit;

SQL> select * from funny;

ID MY_VALUE
============ =====================
10 <null>
20 20.20

SQL> update funny set my_value=my_value + 10;
SQL> commit;

SQL> select * from funny;

ID MY_VALUE
============ =====================
10 <null>
20 30.20

SQL> commit;

If you have a null "value" in a column, you cannot add, subtract etc
that null value. So, changes to "some" values don't seem to work.

The solution in this case is to update the table converting NULL into
0.0 and then adding a NOT NULL constraint to the column in question.
Unfortunatley, this will have to be done by creating a new column with
NOT NULL, copying the existing values over to it, dropping the old
column and renaming the new one.

Unless, of course, it's possibly (now) to do an ALTER table ... alter
column ... not null - which I've been unable to find by experiment or in
the release notes etc!


Cheers,
Norman.







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