Submitting data is new ( not duplicate)

[Yoursnani]

Hi 

I am creating a form that hold employee details . we have text columns,people columns,and date columns 

My scenario is 

When user save data people columns is submitting person columns . when user first time submit form it should save, if user submit with same name in people columns ,form not to submit ? 

how can we achieve this ? 

[Abhilash_Swain]

@Yoursnani ,
 One way of restricting -> If this is a share point list declare the column as Unique and required. It will not save the record.

OR
You can get the current employee names into a collection on APP Start. validate the textbox if the employee exist

I have used this in a Label control - Text.

If (!IsBlank(First(Filter(Employee_Office,Ename.Email = User().Email)).Ename.DisplayName ),"User Exist","")

Employee_Office:- is my SharePoint list and Ename is a people picker
So whenever there is a user of the same email id appears, It displays user exist. You can disable buttons to save the forms .