I'm using Class::DBI for the first time for a project I'm working on at the moment. I've tinkered in the past but I have a new question for you. One that I can't find in the docs.

I have a many-to-many relationship. The docs explain how to do this and it makes some sense. However, when I'm not using Class::DBI it's easy to created a conditional many-to-many relationship. One that has an expiry. Consider this data: 

 User | Group | Expires
------+-------+------------
 1    | 1     | 2004-11-11
 2    | 1     | 2005-01-01
 3    | 1     | 2003-12-31
 3    | 2     | 2005-01-01

SELECT User FROM Subscription WHERE Group = 1 AND Expires > now();
# 1, 2

SELECT Group FROM Subscription WHERE User = 3 AND Expires > now();
# 2

[download]
In an ordinary many-to-many, user 1 is in group 1, user 2 is in group 1 and user 3 is in both 1 and 2. However in this case user 3 should not be in group 1. His membership in that group has expired.

Wise monks, using Class::DBI how would I make that happen?

Note 1: There's also a live date -- the date at which point the subscription starts. However I felt that once I get the expiry worked out, the start date will be easy.

Note 2: When creating a new subscription, the old one should not be overwritten. Should User 3 become a member of group 1 at some later stage, then it would be a new record in the subscription table. This will allow historic queries like "Who was in group 1 on 2004-01-01?"


Cheers!
Rick
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In reply to Conditional many to many relationships with Class::DBI by BigLug

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