Umbrella locks
Leaving your umbrella under your chair, or leaning it up in the corner by the door with the hopes that it won’t be stolen (and you’ll remember it when you go) is so last year.
The more civilized way to ensure you stay dry is to pop your umbrella in one of these locks, just like the bike locks you’d find at stations. This way only you can retrieve your umbrella and you don’t have to deal with it being kicked about under the table all through dinner.