Concurrent Data Entry in Forms

I think this problem is a little be harder than you may think. Basically you need a way to create a lock on a record to the exclusion of others that may be attempting to create a lock on the same record. In Computer Science this lock is called a mutex and it can be a difficult subject to understand and implement.

I haven't worked out all the details but you might be able to create a lock on a record (the time slot) by associating a unique ID for the record. Then all users that might want to attempt to lock that record would create record in a secondary lock table using API_AddRecord where there is a field that has the unique property set. The first API call that reaches QuickBase will successfully create the record in the second table but all other users would receive Error Code 51 (Attempting to add a non-unique value to a field marked "unique"). Now the user that successfully created the record in the secondary table can be allowed through client side logic to claim / edit the desired record in the original table and subsequently delete the record in the secondary table (so it does not grow endlessly).