Filter data based on criteria not in specific row

[cfoster34]

Hi All,

I am new to AppSheet and development so this may be an easy questions. I am making a resource booking app for our little league so coaches can book open locations for practice. I have a practice table with locations and times and when a user selects a practice their email is added to that row which indicates they have reserved it. I slice the practice table for different menus. One is open practices which shows rows where the email field is blank (no one has reserved it). That is working well.

I am trying to stop coaches from claiming all the open practices so I have a field in the practices table for rounds. I would like a coach to only be able to select one practice per round. I was thinking I could do this one of two ways: 1) slice the view so coaches can not see a location for a round they have already reserved or 2) set a condition on the action to not allow for a reservation if the user has already reserved for that round. Unfortunately I am at a loss to write either expression.

The practice table looks like this:

Any help to create the expression to slice or the action condition would be greatly appreciated!

[Marc_Dillon]

ISBLANK( FILTER(
  table ,
  AND(
    [coach] = USEREMAIL() ,
    [round] = [_THISROW].[round]
  )
) )