You have a many-to-many relationship you need to resolve and filtering will come easier as the next step.
Add a table to store seat id and event id as a join table between seat and event. This will allow to record which seats were taken.
Here is another link to the dwindling lists description:
And just to round out the list of helpful resources, here's a fully documented and annotated file of enhanced value selection techniques, one of which happens to be a dwindling value list:
Please note that this file is slated for an upgrade by the end of this week. The upgrade won't affect this issue, but two new topics will be added at that time.
Edit Note: I posted the link to #2 when I should have posted a link to #1. But if you click to the resources page, you'll find a download link to #1.
this was exactly what i needed , thank you. now i just need to figure out how to get it show store the seat.id and show user he seat.name