Just normalize your model properly:
create table user_rank
(
   id integer primary key, -- no identity, so you can control the values
   rank varchar(20) not null unique
);
insert into user_rank (id, rank)
values
  (1, 'Fresh Meat'),
  (2, 'Intern'),
  (3, 'Janitor'),
  (4, 'Lieutenant'),
  (5, 'Supreme being');
CREATE TABLE [users]
(
   ID INT NOT NULL IDENTITY(1,1) PRIMARY KEY,
   username varchar(255),
   password varchar(255),
   mail varchar (255),
   rank integer not null default 1, 
   constraint fk_user_rank foreign key (rank) references user_rank (id)
);
I hope this helps you.
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