# Disallow multiple "reservations" off of my "inventory" list

**URL:** https://community.glideapps.com/t/disallow-multiple-reservations-off-of-my-inventory-list/14995
**Category:** Ask for Help
**Created:** [August 31, 2020, 3:30am UTC](https://community.glideapps.com/t/disallow-multiple-reservations-off-of-my-inventory-list/14995 "2020-08-31T03:30:17Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![joey](https://sea2.discourse-cdn.com/flex002/user_avatar/community.glideapps.com/joey/32/12748_2.png) [@joey](https://community.glideapps.com/u/joey)
#### Post date: [August 31, 2020, 3:30am UTC](https://community.glideapps.com/t/disallow-multiple-reservations-off-of-my-inventory-list/14995/1 "2020-08-31T03:30:17Z")

</div>

Hi all, first post!

I have an app with an inventory of items. Users are allowed to “reserve” some quantity of each item. From my inventory tab, I open a form that writes a row to a “reservations” tab.

What I want to prevent is users being able to reserve the same item again… basically each row in the reservations tab should have a unique item-user column pair.

Right now I am fixing multiple reservations of that kind via a timed spreadsheet script. Not ideal as it still allows users to make these multiple reservations, affecting the available quantity for other users until the script triggers.

How can I selectively allow a user to make a reservation based on them NOT having a corresponding row in the reservations tab?

I feel like “user specific column” on the inventory tab would really solve this, but I know I’m not allowed do much math with those data in that column.

I may be butchering this description, but don’t want to type a novel that probably won’t help things. Happy to follow up with more details. I feel like there is a reasonable solution somewhere. I’m also happy to read blogs or watch videos if anyone thinks a particular one will help.