On 13/11/2010 9:48 AM, flebber wrote:
Hi
Looking for a little assistance. I am trying to create a basic
database schema using Ruby, Sequel and Sqlite3.
I am reading here
http://sequel.rubyforge.org/rdoc/classes/Sequel/Database.html#M000510
and http://www.firstsql.com/tutor6.htm .
The only thing that would be unusual about my db is that I want to use
two primary keys time& date as no more than one event can occur at
any time though multiple events could occur on a day. I am not
understanding in sequel how to correctly create a db with multiple
keys? Or should I just be generating a random number to create a key
which references date and time?
I would be very reluctant to use a random number as the primary key as
you can never guarantee that you aren't going to generate the key more
than once. Then you'll end up having to put in special code to handle
those conflicts.
The more usual design here would be to have the id (primary key) column
as an integer autoincrement so that each time you insert a new record
you get the next higher id automatically assigned by the database
engine. This also plays well with how Sequel models work.
I notice you also have an "EventNumber". Can this be the integer primary
key (with autoincrement). That way you'll have your primary key and
automatically generate your unique event numbers.
As for the date & time columns, just put a unique index on them. That
will also satisfy your unique requirement for those columns.
Cheers,
Gary.
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