MS SQL insert or update if record exists

MS SQL:

if not exists (select 1 from employees where employee_id = 1)
      insert into employees (employee_id,last_name,first_name) values ( 1,'smith', 'bob' )
else
      update employees set last_name='smith' , first_name='bob' where employee_id =   
end 

Above snippet found here:
https://www.withdata.com/blog/sql-server/replace-update-or-insert-a-row-into-sql-server-table.html

Same thing in

MySQL:

INSERT INTO table (id, name, age) VALUES(1, "A", 19) ON DUPLICATE KEY UPDATE    
name="A", age=19