Re: [sqlite] GUID in place of AUTO_INCREMENT
On Jan 25, 2006, at 10:00 AM, Kurt Welgehausen wrote: ... but Rails doesn't seem to support composite keys. I don't know much about RoR. How does RoR keep you from creating a multi-column key on an SQLite table? Regards In point of fact, it doesn't prevent me from *creating* a multi- column key, just from using it effectively. It's just that Rails' implementation of ActiveRecord doesn't understand multi-column PKs. As you might suspect, ActiveRecord handles the relationships between records, and that's a lot easier when PKs and FKs are single-column and follow a reasonable naming convention. At any rate, Dr. Hipp's suggestion of the AFTER INSERT trigger was exactly what I needed. Thanks! -Mike Ashmore
Re: [sqlite] GUID in place of AUTO_INCREMENT
Mike Ashmore <[EMAIL PROTECTED]> wrote: > So, I've got what I think is a good reason to modify the behavior of > primary keys in my (Ruby on Rails-based) application. > > What I need is a modifier, say 'GUID', that can be applied in place > of (mutually exclusive with) the AUTOINCREMENT modifier [1]. On a > field with the GUID modifier, if an INSERT statement proffers a NULL > value for that field, an RFC4122-compliant GUID generator should be > invoked to create a globally unique value for that field. > You can do this with an insert trigger. First create a user-defined function to generate your guid. Suppose that function is named new_guid(). Further suppose that the column that wants the guid is called "pk". Then write the trigger like this: CREATE TRIGGER AFTER INSERT ON table1 WHEN new.pk IS NULL BEGIN UPDATE table1 SET pk=new_guid() WHERE rowid=new.rowid; END; -- D. Richard Hipp <[EMAIL PROTECTED]>
Re: [sqlite] GUID in place of AUTO_INCREMENT
> ... but Rails doesn't seem to support composite keys. I don't know much about RoR. How does RoR keep you from creating a multi-column key on an SQLite table? Regards
