johnblack - 9:25 am on Jan 16, 2011 (gmt 0)
I think what he's asking is how to update a many-many relationship table, sometimes called a join table. In the example there would be a category and event table with a join table called category_event for example.
Other than deleting the existing records and inserting new ones as you suggest, there's no 'neat' way of doing it. The only thing I could think of is to update the existing records with the new category (assuming the input screen is event based). However what happens if the number of categories for the event changes? Then you still have to delete or insert records into the join table.
I think what you have come up with is the best way.