Hi,
I'm just exploring the db.tuples vocabulary, it's fantastic.
Unfortunately there's rather little documentation, so I had to figure
out some things myself. For Example: when I define a slot as
+foreign-key+, there are certain useful triggers inserted in my db. It
is not allowed then, to insert a tuple, with that slot set to f (=
NULL). Isn't that, what the flag +not-null+ should add?
However, when I add the rather confusingly named +not-null+ to the
declaration, the trigger is more complex. I _think_ it should allow
for tuples, that have either a valid foreign id set in the slot, or f
(= NULL).
In sqlite.factor:243 (in insert-trigger-not-null) it says:
WHERE NEW.${foreign-table-id} IS NOT NULL
AND (SELECT ${foreign-table-id} FROM ${foreign-table}
WHERE ${foreign-table-id} = NEW.${table-id}) IS NULL;
That does not make much sense to me, since it asks for the ID-column
of the foreign table _from the current table_. Ids are always called
"ID" in my case, so at first it didn't matter. But it won't allow you
to insert a tuple with a foreign-id = NULL. So I think it should be:
WHERE NEW.${table-id} IS NOT NULL
AND (SELECT ${foreign-table-id} FROM ${foreign-table}
WHERE ${foreign-table-id} = NEW.${table-id}) IS NULL;
${table-id} being the column-name of the foreign id in the current
table. It's still weird though, since that is the behaviour the
trigger should have in case +not-null+ is _not_ given. I'm thoroughly
confused.
Please, help.
Ben
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