Blocking duplicates

[magucio]

Hello,

I am currently at the stage of creating an application for reporting incidents with forklifts. All data is saved to a Google Sheets file and the report is sent via email to the maintenance department with all details of the case. Since more than 50 people will have access to the application, I do not want to allow duplicate incidents because it can cause confusion in your daily work. For example, if someone reported a problem with forklift number 100 and it is a battery problem, I would like the application to prevent the user from reporting the same problem a second time. 
How can I do this? How can the application check whether such a problem has already been reported?

Thank you in advance for any suggestions and answers

[lynchk21]

Depending on the structure of your tables, you should be able to use an expression in valid_if to check if the current issue as been reported. Something like NOT(IN([_this],Select(ActiveReports[Issue],[forkliftID]=[_thisRow].[forkliftID])))