SQL Server 2019

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CREATE TABLE [dbo].[person](        
    [first_name] [nvarchar](200) NULL,
    [last_name] [nvarchar](200) NULL
) ON [PRIMARY]
insert into person (first_name, last_name) values ('Mickey', 'Mouse')
1 rows affected

select * from person


first_name
last_name


Mickey
Mouse


alter table person add display_name as (concat(first_name, ' ', last_name));
select *
from person


first_name
last_name
display_name


Mickey
Mouse
Mickey Mouse


insert into person (first_name, last_name) values ('Donald', 'Duck')
1 rows affected

select *
from person


first_name
last_name
display_name


Mickey
Mouse
Mickey Mouse

Donald
Duck
Donald Duck