> >
> >update EMPLOYEE set LAST_NAME='XX'
> >where ((LAST_NAME=:old_last_name1) or
> > ((:old_last_name2 is null) and (LAST_NAME is null)))
> >
> >
> >I get -804 Sql error code and Data type unknown message. I tried
> >FIBPlus and IBX, both failed.
> >I found that the problematic part is "(:old_last_name2 is null)"
> >expression.
> >If I remove that there's no trouble. What can I do?
>
> If you have a column name old_last_name2, then just take the colon
> off. You can't parameterise a column name, only a value, i.e.
> column_name = :avalue
>

Old_last_name2 isn't a columname, it's really a parameter. It's an
autogenerated sql statement, which I want to use in a 3-tier
application, when I'm updating the database in the middle-tier using
the deltas send by the clients. Naturally its where-clause contains
more criterias (fields) but they have the same structure. It's aiming
to avoid that a user can overwrite changes written by another user. In
other words: update can be successful only if fieldvalues in the db
are the same as the oldvalues of the delta or both are nulls. I named
old_last_name1 and old_last_name2 parameters differently, but they
would contain the same value, if I could prepare the sql statement.
I think the question is the following: Is Firebrid able to prepare and
execute a statement using a parameter with/in an IS NULL expression?

Thanks in advance
Tamas Varga


P.S. Sorry for my English, I hope you understand me.