Why isn't my default value used?
If you have a table with some column defined as NOT NULL DEFAULT 'something' you might get surprise when you try to insert NULL into such column. Example:
create table T1 ( x integer, y integer not null default 10 );
insert into T1(x, y) values (5, null);
You expect that 10 gets written to column y, but you get error message instead.
The reason is that the default values are only used when you don't insert into such column at all:
insert into T1(x) values(5);
What of all your columns have defaults and you want them all? Well, Firebird 2.1 should support such inserts once the final version is out.