How to fix the error of creating a unique index on NVARCHAR(MAX)?

Question

SQL Server

I need to create table Faculties SQL query but row

Dean nvarchar(max) NOT NULL check(Dean != '') unique,

returns an error:

Msg 1919, Level 16, State 1, Line 7
Тип столбца "Dean" в таблице "Faculties" не позволяет выбрать его в качестве ключевого столбца индекса.

Here is the code for the rest of the table:

CREATE TABLE Faculties(
  Id int primary key NOT NULL IDENTITY(1,1),
  Dean nvarchar(max) NOT NULL check(Dean != '') unique,
  [Name] nvarchar(100) NOT NULL check([Name] != '') unique
)

Answer 1

NVARCHAR(MAX)not indexed.

CREATE TABLE Faculties(
  ID INT PRIMARY KEY NOT NULL IDENTITY(1,1),
  Dean NVARCHAR(MAX) NOT NULL CHECK(Dean<>''),
  DeanIndex AS HASHBYTES('SHA',Dean) UNIQUE,
  Name NVARCHAR(100) NOT NULL CHECK(Name<>'') UNIQUE
)

Answer 2

The length of nvarchar(max) is up to 2 ³¹ -1 bytes.
The length of a non-clustered key is 1700 bytes.
It is logical that the field does not fit into the key.
Are you sure you have deans with such long names?
And for good, this field should contain the id of the dean in the table of employees.